Part 3 of immutable Extension refactor.

Make ExtensionsService hold const Extension pointers only. This ensures that
extensions can't be modified after they're created, and lets us share them
between threads.

BUG=56558
TEST=no functional change

Review URL: http://codereview.chromium.org/4138006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@64517 0039d316-1c4b-4281-b951-d872f2087c98

71 files changed, 329 insertions, 314 deletions

diff --git a/chrome/browser/extensions/alert_apitest.cc b/chrome/browser/extensions/alert_apitest.cc
index 23e8fe8..8e70fdb 100644
--- a/chrome/browser/extensions/alert_apitest.cc
+++ b/chrome/browser/extensions/alert_apitest.cc
@@ -14,7 +14,7 @@
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, AlertBasic) {
   ASSERT_TRUE(RunExtensionTest("alert")) << message_;
 
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ExtensionHost* host = browser()->profile()->GetExtensionProcessManager()->
       GetBackgroundHostForExtension(extension);
   ASSERT_TRUE(host);
diff --git a/chrome/browser/extensions/browser_action_apitest.cc b/chrome/browser/extensions/browser_action_apitest.cc
index 8b09783..5e76310 100644
--- a/chrome/browser/extensions/browser_action_apitest.cc
+++ b/chrome/browser/extensions/browser_action_apitest.cc
@@ -47,7 +47,7 @@ class BrowserActionApiTest : public ExtensionApiTest {
 IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, Basic) {
   ASSERT_TRUE(test_server()->Start());
   ASSERT_TRUE(RunExtensionTest("browser_action/basics")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   // Test that there is a browser action in the toolbar.
@@ -87,7 +87,7 @@ IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, Basic) {
 
 IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, DynamicBrowserAction) {
   ASSERT_TRUE(RunExtensionTest("browser_action/no_icon")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   // Test that there is a browser action in the toolbar and that it has no icon.
@@ -117,7 +117,7 @@ IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, DynamicBrowserAction) {
 IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, TabSpecificBrowserActionState) {
   ASSERT_TRUE(RunExtensionTest("browser_action/tab_specific_state")) <<
       message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   // Test that there is a browser action in the toolbar and that it has an icon.
@@ -147,7 +147,7 @@ IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, BrowserActionPopup) {
   ASSERT_TRUE(LoadExtension(test_data_dir_.AppendASCII(
       "browser_action/popup")));
   BrowserActionTestUtil actions_bar = GetBrowserActionsBar();
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   // The extension's popup's size grows by |growFactor| each click.
@@ -180,7 +180,7 @@ IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, BrowserActionPopup) {
 // a popup.
 IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, BrowserActionAddPopup) {
   ASSERT_TRUE(RunExtensionTest("browser_action/add_popup")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   int tab_id = ExtensionTabUtil::GetTabId(browser()->GetSelectedTabContents());
@@ -235,7 +235,7 @@ IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, BrowserActionAddPopup) {
 IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, BrowserActionRemovePopup) {
   // Load the extension, which has a browser action with a default popup.
   ASSERT_TRUE(RunExtensionTest("browser_action/remove_popup")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   int tab_id = ExtensionTabUtil::GetTabId(browser()->GetSelectedTabContents());
@@ -269,7 +269,7 @@ IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, IncognitoBasic) {
   ASSERT_TRUE(test_server()->Start());
 
   ASSERT_TRUE(RunExtensionTest("browser_action/basics")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   // Test that there is a browser action in the toolbar.
diff --git a/chrome/browser/extensions/crx_installer.cc b/chrome/browser/extensions/crx_installer.cc
index 07aa3d08..17276f7 100644
--- a/chrome/browser/extensions/crx_installer.cc
+++ b/chrome/browser/extensions/crx_installer.cc
@@ -157,7 +157,8 @@ void CrxInstaller::ConvertUserScriptOnFileThread() {
   OnUnpackSuccess(extension->path(), extension->path(), extension);
 }
 
-bool CrxInstaller::AllowInstall(Extension* extension, std::string* error) {
+bool CrxInstaller::AllowInstall(const Extension* extension,
+                                std::string* error) {
   DCHECK(error);
 
   // We always allow themes and external installs.
@@ -239,7 +240,7 @@ void CrxInstaller::OnUnpackFailure(const std::string& error_message) {
 
 void CrxInstaller::OnUnpackSuccess(const FilePath& temp_dir,
                                    const FilePath& extension_dir,
-                                   Extension* extension) {
+                                   const Extension* extension) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 
   // Note: We take ownership of |extension| and |temp_dir|.
@@ -282,7 +283,7 @@ void CrxInstaller::ConfirmInstall() {
   }
 
   GURL overlapping_url;
-  Extension* overlapping_extension =
+  const Extension* overlapping_extension =
       frontend_->GetExtensionByOverlappingWebExtent(extension_->web_extent());
   if (overlapping_extension) {
     ReportFailureFromUIThread(l10n_util::GetStringFUTF8(
diff --git a/chrome/browser/extensions/crx_installer.h b/chrome/browser/extensions/crx_installer.h
index 8263095..73d5af8 100644
--- a/chrome/browser/extensions/crx_installer.h
+++ b/chrome/browser/extensions/crx_installer.h
@@ -120,13 +120,13 @@ class CrxInstaller
 
   // Called after OnUnpackSuccess as a last check to see whether the install
   // should complete.
-  bool AllowInstall(Extension* extension, std::string* error);
+  bool AllowInstall(const Extension* extension, std::string* error);
 
   // SandboxedExtensionUnpackerClient
   virtual void OnUnpackFailure(const std::string& error_message);
   virtual void OnUnpackSuccess(const FilePath& temp_dir,
                                const FilePath& extension_dir,
-                               Extension* extension);
+                               const Extension* extension);
 
   // Runs on the UI thread. Confirms with the user (via ExtensionInstallUI) that
   // it is OK to install this extension.
@@ -187,7 +187,7 @@ class CrxInstaller
 
   // The extension we're installing. We own this and either pass it off to
   // ExtensionsService on success, or delete it on failure.
-  scoped_refptr<Extension> extension_;
+  scoped_refptr<const Extension> extension_;
 
   // If non-empty, contains the current version of the extension we're
   // installing (for upgrades).
diff --git a/chrome/browser/extensions/execute_code_in_tab_function.cc b/chrome/browser/extensions/execute_code_in_tab_function.cc
index b7bf999..8021e6c 100644
--- a/chrome/browser/extensions/execute_code_in_tab_function.cc
+++ b/chrome/browser/extensions/execute_code_in_tab_function.cc
@@ -78,7 +78,7 @@ bool ExecuteCodeInTabFunction::RunImpl() {
 
   // NOTE: This can give the wrong answer due to race conditions, but it is OK,
   // we check again in the renderer.
-  Extension* extension = GetExtension();
+  const Extension* extension = GetExtension();
   const std::vector<URLPattern> host_permissions =
       extension->host_permissions();
   if (!Extension::CanExecuteScriptOnPage(
@@ -158,7 +158,7 @@ bool ExecuteCodeInTabFunction::Execute(const std::string& code_string) {
     return false;
   }
 
-  Extension* extension = GetExtension();
+  const Extension* extension = GetExtension();
   if (!extension) {
     SendResponse(false);
     return false;
diff --git a/chrome/browser/extensions/extension_apitest.cc b/chrome/browser/extensions/extension_apitest.cc
index 0547554..07668b3 100644
--- a/chrome/browser/extensions/extension_apitest.cc
+++ b/chrome/browser/extensions/extension_apitest.cc
@@ -144,7 +144,7 @@ bool ExtensionApiTest::RunExtensionTestImpl(const char* extension_name,
           "Relative page_url given with no extension_name";
 
       ExtensionsService* service = browser()->profile()->GetExtensionsService();
-      Extension* extension =
+      const Extension* extension =
           service->GetExtensionById(last_loaded_extension_id_, false);
       if (!extension)
         return false;
@@ -165,7 +165,7 @@ bool ExtensionApiTest::RunExtensionTestImpl(const char* extension_name,
 }
 
 // Test that exactly one extension loaded.
-Extension* ExtensionApiTest::GetSingleLoadedExtension() {
+const Extension* ExtensionApiTest::GetSingleLoadedExtension() {
   ExtensionsService* service = browser()->profile()->GetExtensionsService();
 
   int found_extension_index = -1;
@@ -185,7 +185,7 @@ Extension* ExtensionApiTest::GetSingleLoadedExtension() {
     found_extension_index = static_cast<int>(i);
   }
 
-  Extension* extension = service->extensions()->at(found_extension_index);
+  const Extension* extension = service->extensions()->at(found_extension_index);
   if (!extension) {
     message_ = "extension pointer is NULL.";
     return NULL;
diff --git a/chrome/browser/extensions/extension_apitest.h b/chrome/browser/extensions/extension_apitest.h
index b0a0e01..b2079a6 100644
--- a/chrome/browser/extensions/extension_apitest.h
+++ b/chrome/browser/extensions/extension_apitest.h
@@ -94,7 +94,7 @@ class ExtensionApiTest : public ExtensionBrowserTest {
 
   // Test that exactly one extension loaded.  If so, return a pointer to
   // the extension.  If not, return NULL and set message_.
-  Extension* GetSingleLoadedExtension();
+  const Extension* GetSingleLoadedExtension();
 
   // All extensions tested by ExtensionApiTest are in the "api_test" dir.
   virtual void SetUpCommandLine(CommandLine* command_line);
diff --git a/chrome/browser/extensions/extension_browser_actions_api.cc b/chrome/browser/extensions/extension_browser_actions_api.cc
index 1ce4dfe..1986d28 100644
--- a/chrome/browser/extensions/extension_browser_actions_api.cc
+++ b/chrome/browser/extensions/extension_browser_actions_api.cc
@@ -26,7 +26,7 @@ bool BrowserActionFunction::RunImpl() {
   if (details_->HasKey("tabId"))
     EXTENSION_FUNCTION_VALIDATE(details_->GetInteger("tabId", &tab_id_));
 
-  Extension* extension = GetExtension();
+  const Extension* extension = GetExtension();
   browser_action_ = extension->browser_action();
   if (!browser_action_) {
     error_ = kNoBrowserActionError;
diff --git a/chrome/browser/extensions/extension_browsertest.cc b/chrome/browser/extensions/extension_browsertest.cc
index 7c4cd83..af8a6de 100644
--- a/chrome/browser/extensions/extension_browsertest.cc
+++ b/chrome/browser/extensions/extension_browsertest.cc
@@ -69,7 +69,7 @@ bool ExtensionBrowserTest::LoadExtensionImpl(const FilePath& path,
   // Find the extension by iterating backwards since it is likely last.
   FilePath extension_path = path;
   file_util::AbsolutePath(&extension_path);
-  Extension* extension = NULL;
+  const Extension* extension = NULL;
   for (ExtensionList::const_reverse_iterator iter =
            service->extensions()->rbegin();
        iter != service->extensions()->rend(); ++iter) {
@@ -107,14 +107,15 @@ class MockAbortExtensionInstallUI : public ExtensionInstallUI {
   MockAbortExtensionInstallUI() : ExtensionInstallUI(NULL) {}
 
   // Simulate a user abort on an extension installation.
-  virtual void ConfirmInstall(Delegate* delegate, Extension* extension) {
+  virtual void ConfirmInstall(Delegate* delegate, const Extension* extension) {
     delegate->InstallUIAbort();
     MessageLoopForUI::current()->Quit();
   }
 
-  virtual void ConfirmUninstall(Delegate* delegate, Extension* extension) {}
+  virtual void ConfirmUninstall(Delegate* delegate,
+                                const Extension* extension) {}
 
-  virtual void OnInstallSuccess(Extension* extension) {}
+  virtual void OnInstallSuccess(const Extension* extension) {}
 
   virtual void OnInstallFailure(const std::string& error) {}
 };
@@ -288,7 +289,7 @@ void ExtensionBrowserTest::Observe(NotificationType type,
                                    const NotificationDetails& details) {
   switch (type.value) {
     case NotificationType::EXTENSION_LOADED:
-      last_loaded_extension_id_ = Details<Extension>(details).ptr()->id();
+      last_loaded_extension_id_ = Details<const Extension>(details).ptr()->id();
       VLOG(1) << "Got EXTENSION_LOADED notification.";
       MessageLoopForUI::current()->Quit();
       break;
diff --git a/chrome/browser/extensions/extension_browsertests_misc.cc b/chrome/browser/extensions/extension_browsertests_misc.cc
index 903e0ff..3b1780d 100644
--- a/chrome/browser/extensions/extension_browsertests_misc.cc
+++ b/chrome/browser/extensions/extension_browsertests_misc.cc
@@ -260,13 +260,13 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, PageActionRefreshCrash) {
   ASSERT_TRUE(LoadExtension(base_path.AppendASCII("ExtA")));
   ASSERT_TRUE(WaitForPageActionVisibilityChangeTo(1));
   ASSERT_EQ(size_before + 1, service->extensions()->size());
-  Extension* extensionA = service->extensions()->at(size_before);
+  const Extension* extensionA = service->extensions()->at(size_before);
 
   // Load extension B.
   ASSERT_TRUE(LoadExtension(base_path.AppendASCII("ExtB")));
   ASSERT_TRUE(WaitForPageActionVisibilityChangeTo(2));
   ASSERT_EQ(size_before + 2, service->extensions()->size());
-  Extension* extensionB = service->extensions()->at(size_before + 1);
+  const Extension* extensionB = service->extensions()->at(size_before + 1);
 
   ReloadExtension(extensionA->id());
   // ExtensionA has changed, so refetch it.
@@ -306,7 +306,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, TitleLocalizationBrowserAction) {
   ASSERT_TRUE(LoadExtension(extension_path));
 
   ASSERT_EQ(size_before + 1, service->extensions()->size());
-  Extension* extension = service->extensions()->at(size_before);
+  const Extension* extension = service->extensions()->at(size_before);
 
   EXPECT_STREQ(WideToUTF8(L"Hreggvi\u00F0ur: l10n browser action").c_str(),
                extension->description().c_str());
@@ -335,7 +335,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, TitleLocalizationPageAction) {
   ASSERT_TRUE(WaitForPageActionVisibilityChangeTo(1));
 
   ASSERT_EQ(size_before + 1, service->extensions()->size());
-  Extension* extension = service->extensions()->at(size_before);
+  const Extension* extension = service->extensions()->at(size_before);
 
   EXPECT_STREQ(WideToUTF8(L"Hreggvi\u00F0ur: l10n page action").c_str(),
                extension->description().c_str());
@@ -422,7 +422,7 @@ void NavigateToFeedAndValidate(net::TestServer* server,
   }
 
   ExtensionsService* service = browser->profile()->GetExtensionsService();
-  Extension* extension = service->extensions()->back();
+  const Extension* extension = service->extensions()->back();
   std::string id = extension->id();
 
   // Navigate to the subscribe page directly.
@@ -778,7 +778,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_OptionsPage) {
   ExtensionsService* service = browser()->profile()->GetExtensionsService();
   const ExtensionList* extensions = service->extensions();
   ASSERT_EQ(1u, extensions->size());
-  Extension* extension = extensions->at(0);
+  const Extension* extension = extensions->at(0);
 
   // Go to the chrome://extensions page and click the Options button.
   ui_test_utils::NavigateToURL(browser(), GURL(chrome::kChromeUIExtensionsURL));
diff --git a/chrome/browser/extensions/extension_context_menu_browsertest.cc b/chrome/browser/extensions/extension_context_menu_browsertest.cc
index 62221e1..b0041ad 100644
--- a/chrome/browser/extensions/extension_context_menu_browsertest.cc
+++ b/chrome/browser/extensions/extension_context_menu_browsertest.cc
@@ -142,7 +142,7 @@ class ExtensionContextMenuBrowserTest : public ExtensionBrowserTest {
 
   // Returns a pointer to the currently loaded extension with |name|, or null
   // if not found.
-  Extension* GetExtensionNamed(std::string name) {
+  const Extension* GetExtensionNamed(std::string name) {
     const ExtensionList* extensions =
         browser()->profile()->GetExtensionsService()->extensions();
     ExtensionList::const_iterator i;
@@ -301,7 +301,7 @@ static void VerifyMenuForSeparatorsTest(const MenuModel& menu) {
 IN_PROC_BROWSER_TEST_F(ExtensionContextMenuBrowserTest, Separators) {
   // Load the extension.
   ASSERT_TRUE(LoadContextMenuExtension("separators"));
-  Extension* extension = GetExtensionNamed("Separators Test");
+  const Extension* extension = GetExtensionNamed("Separators Test");
   ASSERT_TRUE(extension != NULL);
 
   // Navigate to test1.html inside the extension, which should create a bunch
diff --git a/chrome/browser/extensions/extension_context_menu_model.cc b/chrome/browser/extensions/extension_context_menu_model.cc
index 6432f9d..404241e 100644
--- a/chrome/browser/extensions/extension_context_menu_model.cc
+++ b/chrome/browser/extensions/extension_context_menu_model.cc
@@ -28,7 +28,7 @@ enum MenuEntries {
 };
 
 ExtensionContextMenuModel::ExtensionContextMenuModel(
-    Extension* extension,
+    const Extension* extension,
     Browser* browser,
     PopupDelegate* delegate)
     : ALLOW_THIS_IN_INITIALIZER_LIST(SimpleMenuModel(this)),
@@ -53,7 +53,7 @@ ExtensionContextMenuModel::~ExtensionContextMenuModel() {
 }
 
 void ExtensionContextMenuModel::InitCommonCommands() {
-  Extension* extension = GetExtension();
+  const Extension* extension = GetExtension();
 
   // The extension pointer should only be null if the extension was uninstalled,
   // and since the menu just opened, it should still be installed.
@@ -73,7 +73,7 @@ bool ExtensionContextMenuModel::IsCommandIdChecked(int command_id) const {
 }
 
 bool ExtensionContextMenuModel::IsCommandIdEnabled(int command_id) const {
-  Extension* extension = this->GetExtension();
+  const Extension* extension = this->GetExtension();
   if (!extension)
     return false;
 
@@ -99,7 +99,7 @@ bool ExtensionContextMenuModel::GetAcceleratorForCommandId(
 }
 
 void ExtensionContextMenuModel::ExecuteCommand(int command_id) {
-  Extension* extension = GetExtension();
+  const Extension* extension = GetExtension();
   if (!extension)
     return;
 
@@ -151,7 +151,7 @@ void ExtensionContextMenuModel::InstallUIAbort() {
   Release();
 }
 
-Extension* ExtensionContextMenuModel::GetExtension() const {
+const Extension* ExtensionContextMenuModel::GetExtension() const {
   ExtensionsService* extension_service = profile_->GetExtensionsService();
   return extension_service->GetExtensionById(extension_id_, false);
 }
diff --git a/chrome/browser/extensions/extension_context_menu_model.h b/chrome/browser/extensions/extension_context_menu_model.h
index e7c5b31..89cf3f9 100644
--- a/chrome/browser/extensions/extension_context_menu_model.h
+++ b/chrome/browser/extensions/extension_context_menu_model.h
@@ -37,7 +37,7 @@ class ExtensionContextMenuModel
   // prefs::kExtensionsUIDeveloperMode is enabled then a menu item
   // will be shown for "Inspect Popup" which, when selected, will cause
   // ShowPopupForDevToolsWindow() to be called on |delegate|.
-  ExtensionContextMenuModel(Extension* extension,
+  ExtensionContextMenuModel(const Extension* extension,
                             Browser* browser,
                             PopupDelegate* delegate);
   virtual ~ExtensionContextMenuModel();
@@ -58,7 +58,7 @@ class ExtensionContextMenuModel
 
   // Gets the extension we are displaying the menu for. Returns NULL if the
   // extension has been uninstalled and no longer exists.
-  Extension* GetExtension() const;
+  const Extension* GetExtension() const;
 
   // A copy of the extension's id.
   std::string extension_id_;
diff --git a/chrome/browser/extensions/extension_crash_recovery_browsertest.cc b/chrome/browser/extensions/extension_crash_recovery_browsertest.cc
index 32b67af..3ad8813 100644
--- a/chrome/browser/extensions/extension_crash_recovery_browsertest.cc
+++ b/chrome/browser/extensions/extension_crash_recovery_browsertest.cc
@@ -51,7 +51,8 @@ class ExtensionCrashRecoveryTest : public ExtensionBrowserTest {
 
   void CrashExtension(size_t index) {
     ASSERT_LT(index, GetExtensionsService()->extensions()->size());
-    Extension* extension = GetExtensionsService()->extensions()->at(index);
+    const Extension* extension =
+        GetExtensionsService()->extensions()->at(index);
     ASSERT_TRUE(extension);
     std::string extension_id(extension->id());
     ExtensionHost* extension_host =
@@ -69,7 +70,8 @@ class ExtensionCrashRecoveryTest : public ExtensionBrowserTest {
 
   void CheckExtensionConsistency(size_t index) {
     ASSERT_LT(index, GetExtensionsService()->extensions()->size());
-    Extension* extension = GetExtensionsService()->extensions()->at(index);
+    const Extension* extension =
+        GetExtensionsService()->extensions()->at(index);
     ASSERT_TRUE(extension);
     ExtensionHost* extension_host =
         GetExtensionProcessManager()->GetBackgroundHostForExtension(extension);
@@ -85,7 +87,7 @@ class ExtensionCrashRecoveryTest : public ExtensionBrowserTest {
     const size_t size_before = GetExtensionsService()->extensions()->size();
     ASSERT_TRUE(LoadExtension(
         test_data_dir_.AppendASCII("common").AppendASCII("background_page")));
-    Extension* extension = GetExtensionsService()->extensions()->back();
+    const Extension* extension = GetExtensionsService()->extensions()->back();
     ASSERT_TRUE(extension);
     first_extension_id_ = extension->id();
     CheckExtensionConsistency(size_before);
@@ -95,7 +97,8 @@ class ExtensionCrashRecoveryTest : public ExtensionBrowserTest {
     int offset = GetExtensionsService()->extensions()->size();
     ASSERT_TRUE(LoadExtension(
         test_data_dir_.AppendASCII("install").AppendASCII("install")));
-    Extension* extension = GetExtensionsService()->extensions()->at(offset);
+    const Extension* extension =
+        GetExtensionsService()->extensions()->at(offset);
     ASSERT_TRUE(extension);
     second_extension_id_ = extension->id();
     CheckExtensionConsistency(offset);
diff --git a/chrome/browser/extensions/extension_disabled_infobar_delegate.cc b/chrome/browser/extensions/extension_disabled_infobar_delegate.cc
index 6e51c47..af38e4f 100644
--- a/chrome/browser/extensions/extension_disabled_infobar_delegate.cc
+++ b/chrome/browser/extensions/extension_disabled_infobar_delegate.cc
@@ -26,7 +26,7 @@ class ExtensionDisabledDialogDelegate
  public:
   ExtensionDisabledDialogDelegate(Profile* profile,
                                   ExtensionsService* service,
-                                  Extension* extension)
+                                  const Extension* extension)
         : service_(service), extension_(extension) {
     AddRef();  // Balanced in Proceed or Abort.
 
@@ -55,7 +55,7 @@ class ExtensionDisabledDialogDelegate
   scoped_ptr<ExtensionInstallUI> install_ui_;
 
   ExtensionsService* service_;
-  Extension* extension_;
+  const Extension* extension_;
 };
 
 class ExtensionDisabledInfobarDelegate
@@ -64,7 +64,7 @@ class ExtensionDisabledInfobarDelegate
  public:
   ExtensionDisabledInfobarDelegate(TabContents* tab_contents,
                                    ExtensionsService* service,
-                                   Extension* extension)
+                                   const Extension* extension)
       : ConfirmInfoBarDelegate(tab_contents),
         tab_contents_(tab_contents),
         service_(service),
@@ -110,7 +110,7 @@ class ExtensionDisabledInfobarDelegate
     switch (type.value) {
       case NotificationType::EXTENSION_LOADED:
       case NotificationType::EXTENSION_UNLOADED_DISABLED: {
-        Extension* extension = Details<Extension>(details).ptr();
+        const Extension* extension = Details<const Extension>(details).ptr();
         if (extension == extension_)
           tab_contents_->RemoveInfoBar(this);
         break;
@@ -124,11 +124,11 @@ class ExtensionDisabledInfobarDelegate
   NotificationRegistrar registrar_;
   TabContents* tab_contents_;
   ExtensionsService* service_;
-  Extension* extension_;
+  const Extension* extension_;
 };
 
 void ShowExtensionDisabledUI(ExtensionsService* service, Profile* profile,
-                             Extension* extension) {
+                             const Extension* extension) {
   Browser* browser = BrowserList::GetLastActiveWithProfile(profile);
   if (!browser)
     return;
@@ -142,7 +142,7 @@ void ShowExtensionDisabledUI(ExtensionsService* service, Profile* profile,
 }
 
 void ShowExtensionDisabledDialog(ExtensionsService* service, Profile* profile,
-                                 Extension* extension) {
+                                 const Extension* extension) {
   // This object manages its own lifetime.
   new ExtensionDisabledDialogDelegate(profile, service, extension);
 }
diff --git a/chrome/browser/extensions/extension_disabled_infobar_delegate.h b/chrome/browser/extensions/extension_disabled_infobar_delegate.h
index 16d3b6f..430e652 100644
--- a/chrome/browser/extensions/extension_disabled_infobar_delegate.h
+++ b/chrome/browser/extensions/extension_disabled_infobar_delegate.h
@@ -13,10 +13,10 @@ class Profile;
 // Shows UI to inform the user that an extension was disabled after upgrading
 // to higher permissions.
 void ShowExtensionDisabledUI(ExtensionsService* service, Profile* profile,
-                             Extension* extension);
+                             const Extension* extension);
 
 // Shows the extension install dialog.
 void ShowExtensionDisabledDialog(ExtensionsService* service, Profile* profile,
-                                 Extension* extension);
+                                 const Extension* extension);
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_DISABLED_INFOBAR_DELEGATE_H_
diff --git a/chrome/browser/extensions/extension_dom_ui.cc b/chrome/browser/extensions/extension_dom_ui.cc
index 29c5aab..054eb1e 100644
--- a/chrome/browser/extensions/extension_dom_ui.cc
+++ b/chrome/browser/extensions/extension_dom_ui.cc
@@ -112,7 +112,7 @@ class ExtensionDOMUIImageLoadingTracker : public ImageLoadingTracker::Observer {
 
   ImageLoadingTracker tracker_;
   scoped_refptr<FaviconService::GetFaviconRequest> request_;
-  Extension* extension_;
+  const Extension* extension_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionDOMUIImageLoadingTracker);
 };
@@ -126,7 +126,7 @@ ExtensionDOMUI::ExtensionDOMUI(TabContents* tab_contents, GURL url)
     : DOMUI(tab_contents),
       url_(url) {
   ExtensionsService* service = tab_contents->profile()->GetExtensionsService();
-  Extension* extension = service->GetExtensionByURL(url);
+  const Extension* extension = service->GetExtensionByURL(url);
   if (!extension)
     extension = service->GetExtensionByWebExtent(url);
   DCHECK(extension);
@@ -271,7 +271,7 @@ bool ExtensionDOMUI::HandleChromeURLOverride(GURL* url, Profile* profile) {
     }
 
     // Verify that the extension that's being referred to actually exists.
-    Extension* extension = service->GetExtensionByURL(extension_url);
+    const Extension* extension = service->GetExtensionByURL(extension_url);
     if (!extension) {
       // This can currently happen if you use --load-extension one run, and
       // then don't use it the next.  It could also happen if an extension
diff --git a/chrome/browser/extensions/extension_event_router.cc b/chrome/browser/extensions/extension_event_router.cc
index 9d22da7..b1577167 100644
--- a/chrome/browser/extensions/extension_event_router.cc
+++ b/chrome/browser/extensions/extension_event_router.cc
@@ -38,7 +38,7 @@ static bool CanCrossIncognito(Profile* profile,
   // We allow the extension to see events and data from another profile iff it
   // uses "spanning" behavior and it has incognito access. "split" mode
   // extensions only see events for a matching profile.
-  Extension* extension =
+  const Extension* extension =
       profile->GetExtensionsService()->GetExtensionById(extension_id, false);
   return (profile->GetExtensionsService()->IsIncognitoEnabled(extension) &&
           !extension->incognito_split_mode());
diff --git a/chrome/browser/extensions/extension_function.cc b/chrome/browser/extensions/extension_function.cc
index f285e9d..88a6c9e 100644
--- a/chrome/browser/extensions/extension_function.cc
+++ b/chrome/browser/extensions/extension_function.cc
@@ -21,7 +21,7 @@ ExtensionFunction::ExtensionFunction()
 ExtensionFunction::~ExtensionFunction() {
 }
 
-Extension* ExtensionFunction::GetExtension() {
+const Extension* ExtensionFunction::GetExtension() {
   ExtensionsService* service = profile_->GetExtensionsService();
   DCHECK(service);
   return service->GetExtensionById(extension_id_, false);
diff --git a/chrome/browser/extensions/extension_function.h b/chrome/browser/extensions/extension_function.h
index b48d0a9..57a8665 100644
--- a/chrome/browser/extensions/extension_function.h
+++ b/chrome/browser/extensions/extension_function.h
@@ -107,7 +107,7 @@ class ExtensionFunction : public base::RefCountedThreadSafe<ExtensionFunction> {
   // Gets the extension that called this function. This can return NULL for
   // async functions, for example if the extension is unloaded while the
   // function is running.
-  Extension* GetExtension();
+  const Extension* GetExtension();
 
   // Gets the "current" browser, if any.
   //
diff --git a/chrome/browser/extensions/extension_function_dispatcher.cc b/chrome/browser/extensions/extension_function_dispatcher.cc
index e3ca590..783a8bf 100644
--- a/chrome/browser/extensions/extension_function_dispatcher.cc
+++ b/chrome/browser/extensions/extension_function_dispatcher.cc
@@ -341,7 +341,7 @@ ExtensionFunctionDispatcher* ExtensionFunctionDispatcher::Create(
   if (!service->ExtensionBindingsAllowed(url))
     return NULL;
 
-  Extension* extension = service->GetExtensionByURL(url);
+  const Extension* extension = service->GetExtensionByURL(url);
   if (!extension)
     extension = service->GetExtensionByWebExtent(url);
 
@@ -355,7 +355,7 @@ ExtensionFunctionDispatcher* ExtensionFunctionDispatcher::Create(
 ExtensionFunctionDispatcher::ExtensionFunctionDispatcher(
     RenderViewHost* render_view_host,
     Delegate* delegate,
-    Extension* extension,
+    const Extension* extension,
     const GURL& url)
   : profile_(render_view_host->process()->profile()),
     render_view_host_(render_view_host),
@@ -448,7 +448,7 @@ void ExtensionFunctionDispatcher::HandleRequest(
   function->set_user_gesture(params.user_gesture);
   ExtensionsService* service = profile()->GetExtensionsService();
   DCHECK(service);
-  Extension* extension = service->GetExtensionById(extension_id(), false);
+  const Extension* extension = service->GetExtensionById(extension_id(), false);
   DCHECK(extension);
   function->set_include_incognito(service->IsIncognitoEnabled(extension) &&
                                   !extension->incognito_split_mode());
diff --git a/chrome/browser/extensions/extension_function_dispatcher.h b/chrome/browser/extensions/extension_function_dispatcher.h
index 99328f7..9969b1f 100644
--- a/chrome/browser/extensions/extension_function_dispatcher.h
+++ b/chrome/browser/extensions/extension_function_dispatcher.h
@@ -125,7 +125,7 @@ class ExtensionFunctionDispatcher {
  private:
   ExtensionFunctionDispatcher(RenderViewHost* render_view_host,
                               Delegate* delegate,
-                              Extension* extension,
+                              const Extension* extension,
                               const GURL& url);
 
   // We need to keep a pointer to the profile because we use it in the dtor
diff --git a/chrome/browser/extensions/extension_gallery_install_apitest.cc b/chrome/browser/extensions/extension_gallery_install_apitest.cc
index cf10ed4..5dd4811 100644
--- a/chrome/browser/extensions/extension_gallery_install_apitest.cc
+++ b/chrome/browser/extensions/extension_gallery_install_apitest.cc
@@ -24,8 +24,7 @@ class ExtensionGalleryInstallApiTest : public ExtensionApiTest {
 #else
 #define MAYBE_InstallAndUninstall InstallAndUninstall
 #endif
-IN_PROC_BROWSER_TEST_F(ExtensionGalleryInstallApiTest,
-                       MAYBE_InstallAndUninstall) {
+IN_PROC_BROWSER_TEST_F(ExtensionGalleryInstallApiTest, InstallAndUninstall) {
   host_resolver()->AddRule("www.example.com", "127.0.0.1");
   ASSERT_TRUE(test_server()->Start());
 
diff --git a/chrome/browser/extensions/extension_host.cc b/chrome/browser/extensions/extension_host.cc
index d39bcf7..0453880 100644
--- a/chrome/browser/extensions/extension_host.cc
+++ b/chrome/browser/extensions/extension_host.cc
@@ -122,8 +122,10 @@ class ExtensionHost::ProcessCreationQueue {
 ////////////////
 // ExtensionHost
 
-ExtensionHost::ExtensionHost(Extension* extension, SiteInstance* site_instance,
-                             const GURL& url, ViewType::Type host_type)
+ExtensionHost::ExtensionHost(const Extension* extension,
+                             SiteInstance* site_instance,
+                             const GURL& url,
+                             ViewType::Type host_type)
     : extension_(extension),
       profile_(site_instance->browsing_instance()->profile()),
       did_stop_loading_(false),
@@ -265,7 +267,7 @@ void ExtensionHost::Observe(NotificationType type,
       // sent. NULL it out so that dirty pointer issues don't arise in cases
       // when multiple ExtensionHost objects pointing to the same Extension are
       // present.
-      if (extension_ == Details<Extension>(details).ptr())
+      if (extension_ == Details<const Extension>(details).ptr())
         extension_ = NULL;
       break;
     default:
diff --git a/chrome/browser/extensions/extension_host.h b/chrome/browser/extensions/extension_host.h
index cf677e3..bb96c5d 100644
--- a/chrome/browser/extensions/extension_host.h
+++ b/chrome/browser/extensions/extension_host.h
@@ -51,7 +51,7 @@ class ExtensionHost : public RenderViewHostDelegate,
   typedef std::list<ExtensionHost*> HostPointerList;
   static HostPointerList* recently_deleted();
 
-  ExtensionHost(Extension* extension, SiteInstance* site_instance,
+  ExtensionHost(const Extension* extension, SiteInstance* site_instance,
                 const GURL& url, ViewType::Type host_type);
   ~ExtensionHost();
 
@@ -73,7 +73,7 @@ class ExtensionHost : public RenderViewHostDelegate,
   // instantiate Browser objects.
   void CreateView(Browser* browser);
 
-  Extension* extension() { return extension_; }
+  const Extension* extension() { return extension_; }
   RenderViewHost* render_view_host() const { return render_view_host_; }
   RenderProcessHost* render_process_host() const;
   SiteInstance* site_instance() const;
@@ -238,7 +238,7 @@ class ExtensionHost : public RenderViewHostDelegate,
   bool is_background_page() const { return !view(); }
 
   // The extension that we're hosting in this view.
-  Extension* extension_;
+  const Extension* extension_;
 
   // The profile that this host is tied to.
   Profile* profile_;
diff --git a/chrome/browser/extensions/extension_host_mac.h b/chrome/browser/extensions/extension_host_mac.h
index 65aceaa..da46f16 100644
--- a/chrome/browser/extensions/extension_host_mac.h
+++ b/chrome/browser/extensions/extension_host_mac.h
@@ -12,7 +12,7 @@ class RenderWidgetHostView;
 
 class ExtensionHostMac : public ExtensionHost {
  public:
-  ExtensionHostMac(Extension* extension, SiteInstance* site_instance,
+  ExtensionHostMac(const Extension* extension, SiteInstance* site_instance,
                    const GURL& url, ViewType::Type host_type) :
       ExtensionHost(extension, site_instance, url, host_type) {}
   virtual ~ExtensionHostMac();
diff --git a/chrome/browser/extensions/extension_icon_manager.cc b/chrome/browser/extensions/extension_icon_manager.cc
index 53c8923..887dc3ff 100644
--- a/chrome/browser/extensions/extension_icon_manager.cc
+++ b/chrome/browser/extensions/extension_icon_manager.cc
@@ -45,7 +45,7 @@ ExtensionIconManager::ExtensionIconManager()
 ExtensionIconManager::~ExtensionIconManager() {
 }
 
-void ExtensionIconManager::LoadIcon(Extension* extension) {
+void ExtensionIconManager::LoadIcon(const Extension* extension) {
   ExtensionResource icon_resource = extension->GetIconResource(
       Extension::EXTENSION_ICON_BITTY, ExtensionIconSet::MATCH_BIGGER);
   if (!icon_resource.extension_root().empty()) {
diff --git a/chrome/browser/extensions/extension_icon_manager.h b/chrome/browser/extensions/extension_icon_manager.h
index 876f5e0..cc0deb9 100644
--- a/chrome/browser/extensions/extension_icon_manager.h
+++ b/chrome/browser/extensions/extension_icon_manager.h
@@ -23,7 +23,7 @@ class ExtensionIconManager : public ImageLoadingTracker::Observer {
   virtual ~ExtensionIconManager();
 
   // Start loading the icon for the given extension.
-  void LoadIcon(Extension* extension);
+  void LoadIcon(const Extension* extension);
 
   // This returns a bitmap of width/height kFavIconSize, loaded either from an
   // entry specified in the extension's 'icon' section of the manifest, or a
diff --git a/chrome/browser/extensions/extension_infobar_delegate.cc b/chrome/browser/extensions/extension_infobar_delegate.cc
index b3b8a39..0aea7ce 100644
--- a/chrome/browser/extensions/extension_infobar_delegate.cc
+++ b/chrome/browser/extensions/extension_infobar_delegate.cc
@@ -15,7 +15,7 @@
 
 ExtensionInfoBarDelegate::ExtensionInfoBarDelegate(Browser* browser,
                                                    TabContents* tab_contents,
-                                                   Extension* extension,
+                                                   const Extension* extension,
                                                    const GURL& url)
     : InfoBarDelegate(tab_contents),
       observer_(NULL),
@@ -78,7 +78,7 @@ void ExtensionInfoBarDelegate::Observe(NotificationType type,
       break;
     }
     case NotificationType::EXTENSION_UNLOADED: {
-      Extension* extension = Details<Extension>(details).ptr();
+      const Extension* extension = Details<const Extension>(details).ptr();
       if (extension_ == extension)
         tab_contents_->RemoveInfoBar(this);
       break;
diff --git a/chrome/browser/extensions/extension_infobar_delegate.h b/chrome/browser/extensions/extension_infobar_delegate.h
index dae7aa9..949b655 100644
--- a/chrome/browser/extensions/extension_infobar_delegate.h
+++ b/chrome/browser/extensions/extension_infobar_delegate.h
@@ -28,10 +28,10 @@ class ExtensionInfoBarDelegate : public InfoBarDelegate,
   };
 
   ExtensionInfoBarDelegate(Browser* browser, TabContents* contents,
-                           Extension* extension, const GURL& url);
+                           const Extension* extension, const GURL& url);
   ~ExtensionInfoBarDelegate();
 
-  Extension* extension() { return extension_; }
+  const Extension* extension() { return extension_; }
   ExtensionHost* extension_host() { return extension_host_.get(); }
 
   void set_observer(DelegateObserver* observer) { observer_ = observer; }
@@ -60,7 +60,7 @@ class ExtensionInfoBarDelegate : public InfoBarDelegate,
   // The observer monitoring when the delegate dies.
   DelegateObserver* observer_;
 
-  Extension* extension_;
+  const Extension* extension_;
 
   TabContents* tab_contents_;
 
diff --git a/chrome/browser/extensions/extension_infobar_module.cc b/chrome/browser/extensions/extension_infobar_module.cc
index 590bfc1..6662bea 100644
--- a/chrome/browser/extensions/extension_infobar_module.cc
+++ b/chrome/browser/extensions/extension_infobar_module.cc
@@ -32,7 +32,7 @@ bool ShowInfoBarFunction::RunImpl() {
   std::string html_path;
   EXTENSION_FUNCTION_VALIDATE(args->GetString(keys::kHtmlPath, &html_path));
 
-  Extension* extension = GetExtension();
+  const Extension* extension = GetExtension();
   GURL url = extension->GetResourceURL(extension->url(), html_path);
 
   Browser* browser = NULL;
diff --git a/chrome/browser/extensions/extension_install_ui.cc b/chrome/browser/extensions/extension_install_ui.cc
index b1b2205..3c5f819 100644
--- a/chrome/browser/extensions/extension_install_ui.cc
+++ b/chrome/browser/extensions/extension_install_ui.cc
@@ -82,7 +82,7 @@ ExtensionInstallUI::~ExtensionInstallUI() {
 }
 
 void ExtensionInstallUI::ConfirmInstall(Delegate* delegate,
-                                        Extension* extension) {
+                                        const Extension* extension) {
   DCHECK(ui_loop_ == MessageLoop::current());
   extension_ = extension;
   delegate_ = delegate;
@@ -92,7 +92,7 @@ void ExtensionInstallUI::ConfirmInstall(Delegate* delegate,
   // to allow the user to revert if they don't like it.
   if (extension->is_theme()) {
     // Remember the current theme in case the user pressed undo.
-    Extension* previous_theme = profile_->GetTheme();
+    const Extension* previous_theme = profile_->GetTheme();
     if (previous_theme)
       previous_theme_id_ = previous_theme->id();
 
@@ -113,7 +113,7 @@ void ExtensionInstallUI::ConfirmInstall(Delegate* delegate,
 }
 
 void ExtensionInstallUI::ConfirmUninstall(Delegate* delegate,
-                                          Extension* extension) {
+                                          const Extension* extension) {
   DCHECK(ui_loop_ == MessageLoop::current());
   extension_ = extension;
   delegate_ = delegate;
@@ -121,7 +121,7 @@ void ExtensionInstallUI::ConfirmUninstall(Delegate* delegate,
   ShowConfirmation(UNINSTALL_PROMPT);
 }
 
-void ExtensionInstallUI::OnInstallSuccess(Extension* extension) {
+void ExtensionInstallUI::OnInstallSuccess(const Extension* extension) {
   if (extension->is_theme()) {
     ShowThemeInfoBar(previous_theme_id_, previous_use_system_theme_,
                      extension, profile_);
@@ -226,7 +226,7 @@ void ExtensionInstallUI::OnImageLoaded(
 
 void ExtensionInstallUI::ShowThemeInfoBar(
     const std::string& previous_theme_id, bool previous_use_system_theme,
-    Extension* new_theme, Profile* profile) {
+    const Extension* new_theme, Profile* profile) {
   if (!new_theme->is_theme())
     return;
 
@@ -283,7 +283,7 @@ void ExtensionInstallUI::ShowConfirmation(PromptType prompt_type) {
 
 #if defined(OS_MACOSX)
 void ExtensionInstallUI::ShowGenericExtensionInstalledInfoBar(
-    Extension* new_extension) {
+    const Extension* new_extension) {
   Browser* browser = BrowserList::GetLastActiveWithProfile(profile_);
   if (!browser)
     return;
@@ -304,7 +304,7 @@ void ExtensionInstallUI::ShowGenericExtensionInstalledInfoBar(
 #endif
 
 InfoBarDelegate* ExtensionInstallUI::GetNewThemeInstalledInfoBarDelegate(
-    TabContents* tab_contents, Extension* new_theme,
+    TabContents* tab_contents, const Extension* new_theme,
     const std::string& previous_theme_id, bool previous_use_system_theme) {
 #if defined(TOOLKIT_GTK)
   return new GtkThemeInstalledInfoBarDelegate(tab_contents, new_theme,
diff --git a/chrome/browser/extensions/extension_install_ui.h b/chrome/browser/extensions/extension_install_ui.h
index 7ab2c02..6cc8876 100644
--- a/chrome/browser/extensions/extension_install_ui.h
+++ b/chrome/browser/extensions/extension_install_ui.h
@@ -58,17 +58,17 @@ class ExtensionInstallUI : public ImageLoadingTracker::Observer {
   //
   // We *MUST* eventually call either Proceed() or Abort()
   // on |delegate|.
-  virtual void ConfirmInstall(Delegate* delegate, Extension* extension);
+  virtual void ConfirmInstall(Delegate* delegate, const Extension* extension);
 
   // This is called by the extensions management page to verify whether the
   // uninstallation should proceed. This is declared virtual for testing.
   //
   // We *MUST* eventually call either Proceed() or Abort()
   // on |delegate|.
-  virtual void ConfirmUninstall(Delegate* delegate, Extension* extension);
+  virtual void ConfirmUninstall(Delegate* delegate, const Extension* extension);
 
   // Installation was successful. This is declared virtual for testing.
-  virtual void OnInstallSuccess(Extension* extension);
+  virtual void OnInstallSuccess(const Extension* extension);
 
   // Installation failed. This is declared virtual for testing.
   virtual void OnInstallFailure(const std::string& error);
@@ -85,7 +85,7 @@ class ExtensionInstallUI : public ImageLoadingTracker::Observer {
   // GetNewThemeInstalledInfoBarDelegate()).
   static void ShowThemeInfoBar(
       const std::string& previous_theme_id, bool previous_use_system_theme,
-      Extension* new_theme, Profile* profile);
+      const Extension* new_theme, Profile* profile);
 
  private:
   // Starts the process of showing a confirmation UI, which is split into two.
@@ -96,25 +96,25 @@ class ExtensionInstallUI : public ImageLoadingTracker::Observer {
 #if defined(OS_MACOSX)
   // When an extension is installed on Mac with neither browser action nor
   // page action icons, show an infobar instead of a popup bubble.
-  void ShowGenericExtensionInstalledInfoBar(Extension* new_extension);
+  void ShowGenericExtensionInstalledInfoBar(const Extension* new_extension);
 #endif
 
   // Returns the delegate to control the browser's info bar. This is
   // within its own function due to its platform-specific nature.
   static InfoBarDelegate* GetNewThemeInstalledInfoBarDelegate(
-      TabContents* tab_contents, Extension* new_theme,
+      TabContents* tab_contents, const Extension* new_theme,
       const std::string& previous_theme_id, bool previous_use_system_theme);
 
   // Implements the showing of the install/uninstall dialog prompt.
   // NOTE: The implementations of this function is platform-specific.
   static void ShowExtensionInstallUIPromptImpl(
-      Profile* profile, Delegate* delegate, Extension* extension,
+      Profile* profile, Delegate* delegate, const Extension* extension,
       SkBitmap* icon, PromptType type);
 
   // Implements the showing of the new install dialog. The implementations of
   // this function are platform-specific.
   static void ShowExtensionInstallUIPrompt2Impl(
-      Profile* profile, Delegate* delegate, Extension* extension,
+      Profile* profile, Delegate* delegate, const Extension* extension,
       SkBitmap* icon, const std::vector<string16>& permissions);
 
   Profile* profile_;
@@ -125,7 +125,7 @@ class ExtensionInstallUI : public ImageLoadingTracker::Observer {
   bool previous_use_system_theme_;
 
   SkBitmap icon_;  // The extensions installation icon.
-  Extension* extension_;  // The extension we are showing the UI for.
+  const Extension* extension_;  // The extension we are showing the UI for.
   Delegate* delegate_;    // The delegate we will call Proceed/Abort on after
                           // confirmation UI.
   PromptType prompt_type_;  // The type of prompt we are going to show.
diff --git a/chrome/browser/extensions/extension_install_ui_browsertest.cc b/chrome/browser/extensions/extension_install_ui_browsertest.cc
index 14a6a5b..9a5a9f2 100644
--- a/chrome/browser/extensions/extension_install_ui_browsertest.cc
+++ b/chrome/browser/extensions/extension_install_ui_browsertest.cc
@@ -39,7 +39,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionInstallUIBrowserTest,
   // Install theme once and undo to verify we go back to default theme.
   FilePath theme_path = test_data_dir_.AppendASCII("theme.crx");
   ASSERT_TRUE(InstallExtensionWithUI(theme_path, 1));
-  Extension* theme = browser()->profile()->GetTheme();
+  const Extension* theme = browser()->profile()->GetTheme();
   ASSERT_TRUE(theme);
   ASSERT_EQ(theme_crx, theme->id());
   VerifyThemeInfoBarAndUndoInstall();
diff --git a/chrome/browser/extensions/extension_management_api.cc b/chrome/browser/extensions/extension_management_api.cc
index 50777db..fcf40b8 100644
--- a/chrome/browser/extensions/extension_management_api.cc
+++ b/chrome/browser/extensions/extension_management_api.cc
@@ -107,7 +107,7 @@ bool GetAllExtensionsFunction::RunImpl() {
 bool LaunchAppFunction::RunImpl() {
   std::string extension_id;
   EXTENSION_FUNCTION_VALIDATE(args_->GetString(0, &extension_id));
-  Extension* extension = service()->GetExtensionById(extension_id, true);
+  const Extension* extension = service()->GetExtensionById(extension_id, true);
   if (!extension) {
     error_ = ExtensionErrorUtils::FormatErrorMessage(kNoExtensionError,
                                                      extension_id);
@@ -219,7 +219,7 @@ void ExtensionManagementEventRouter::Observe(
         Details<UninstalledExtensionInfo>(details).ptr()->extension_id;
     args.Append(Value::CreateStringValue(extension_id));
   } else {
-    Extension* extension = Details<Extension>(details).ptr();
+    const Extension* extension = Details<const Extension>(details).ptr();
     CHECK(extension);
     ExtensionsService* service = profile->GetExtensionsService();
     bool enabled = service->GetExtensionById(extension->id(), false) != NULL;
diff --git a/chrome/browser/extensions/extension_management_browsertest.cc b/chrome/browser/extensions/extension_management_browsertest.cc
index e6b1f8f..a80cc8a 100644
--- a/chrome/browser/extensions/extension_management_browsertest.cc
+++ b/chrome/browser/extensions/extension_management_browsertest.cc
@@ -25,7 +25,7 @@ class ExtensionManagementTest : public ExtensionBrowserTest {
   // in the extension's manifest. We use the version as reported by the
   // background page to test how overinstalling crx files with the same
   // manifest version works.
-  bool IsExtensionAtVersion(Extension* extension,
+  bool IsExtensionAtVersion(const Extension* extension,
                             const std::string& expected_version) {
     // Test that the extension's version from the manifest and reported by the
     // background page is correct.  This is to ensure that the processes are in
@@ -171,7 +171,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionManagementTest, DisableEnable) {
                     .AppendASCII("1.0")));
   ASSERT_EQ(size_before + 1, service->extensions()->size());
   EXPECT_EQ(0u, service->disabled_extensions()->size());
-  Extension* extension = service->extensions()->at(size_before);
+  const Extension* extension = service->extensions()->at(size_before);
   EXPECT_TRUE(manager->GetBackgroundHostForExtension(extension));
   ASSERT_TRUE(service->HasInstalledExtensions());
 
diff --git a/chrome/browser/extensions/extension_menu_manager.cc b/chrome/browser/extensions/extension_menu_manager.cc
index 58bd1af..9ddb0f0 100644
--- a/chrome/browser/extensions/extension_menu_manager.cc
+++ b/chrome/browser/extensions/extension_menu_manager.cc
@@ -125,7 +125,7 @@ const ExtensionMenuItem::List* ExtensionMenuManager::MenuItems(
   return NULL;
 }
 
-bool ExtensionMenuManager::AddContextItem(Extension* extension,
+bool ExtensionMenuManager::AddContextItem(const Extension* extension,
                                           ExtensionMenuItem* item) {
   const std::string& extension_id = item->extension_id();
   // The item must have a non-empty extension id, and not have already been
@@ -455,7 +455,7 @@ void ExtensionMenuManager::Observe(NotificationType type,
     NOTREACHED();
     return;
   }
-  Extension* extension = Details<Extension>(details).ptr();
+  const Extension* extension = Details<const Extension>(details).ptr();
   if (ContainsKey(context_items_, extension->id())) {
     RemoveAllContextItems(extension->id());
   }
diff --git a/chrome/browser/extensions/extension_menu_manager.h b/chrome/browser/extensions/extension_menu_manager.h
index 41edb61..4455ee1 100644
--- a/chrome/browser/extensions/extension_menu_manager.h
+++ b/chrome/browser/extensions/extension_menu_manager.h
@@ -198,7 +198,7 @@ class ExtensionMenuManager : public NotificationObserver {
   // Adds a top-level menu item for an extension, requiring the |extension|
   // pointer so it can load the icon for the extension. Takes ownership of
   // |item|. Returns a boolean indicating success or failure.
-  bool AddContextItem(Extension* extension, ExtensionMenuItem* item);
+  bool AddContextItem(const Extension* extension, ExtensionMenuItem* item);
 
   // Add an item as a child of another item which has been previously added, and
   // takes ownership of |item|. Returns a boolean indicating success or failure.
diff --git a/chrome/browser/extensions/extension_menu_manager_unittest.cc b/chrome/browser/extensions/extension_menu_manager_unittest.cc
index 56c95c4..549c245 100644
--- a/chrome/browser/extensions/extension_menu_manager_unittest.cc
+++ b/chrome/browser/extensions/extension_menu_manager_unittest.cc
@@ -323,7 +323,7 @@ TEST_F(ExtensionMenuManagerTest, ExtensionUnloadRemovesMenuItems) {
   // gone.
   notifier->Notify(NotificationType::EXTENSION_UNLOADED,
                    Source<Profile>(NULL),
-                   Details<Extension>(extension1));
+                   Details<const Extension>(extension1));
   ASSERT_EQ(NULL, manager_.MenuItems(extension1->id()));
   ASSERT_EQ(1u, manager_.MenuItems(extension2->id())->size());
   ASSERT_TRUE(manager_.GetItemById(id1) == NULL);
diff --git a/chrome/browser/extensions/extension_metrics_apitest.cc b/chrome/browser/extensions/extension_metrics_apitest.cc
index ee4761c..c9464d2 100644
--- a/chrome/browser/extensions/extension_metrics_apitest.cc
+++ b/chrome/browser/extensions/extension_metrics_apitest.cc
@@ -146,7 +146,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, Metrics) {
   UserActionObserver observer;
 
   ASSERT_TRUE(RunExtensionTest("metrics")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension);
 
   observer.ValidateUserActions(extension,
diff --git a/chrome/browser/extensions/extension_pref_store.cc b/chrome/browser/extensions/extension_pref_store.cc
index 773e94e..27719ed 100644
--- a/chrome/browser/extensions/extension_pref_store.cc
+++ b/chrome/browser/extensions/extension_pref_store.cc
@@ -25,7 +25,7 @@ ExtensionPrefStore::~ExtensionPrefStore() {
   notification_registrar_.RemoveAll();
 }
 
-void ExtensionPrefStore::InstallExtensionPref(Extension* extension,
+void ExtensionPrefStore::InstallExtensionPref(const Extension* extension,
                                               const char* new_pref_path,
                                               Value* new_pref_value) {
   ExtensionStack::iterator i;
@@ -62,7 +62,7 @@ void ExtensionPrefStore::InstallExtensionPref(Extension* extension,
   UpdateOnePref(new_pref_path);
 }
 
-void ExtensionPrefStore::UninstallExtension(Extension* extension) {
+void ExtensionPrefStore::UninstallExtension(const Extension* extension) {
   // Remove this extension from the stack.
   for (ExtensionStack::iterator i = extension_stack_.begin();
       i != extension_stack_.end(); ++i) {
@@ -178,7 +178,7 @@ void ExtensionPrefStore::Observe(NotificationType type,
     }
     case NotificationType::EXTENSION_UNLOADED: {
       Profile* extension_profile = Source<Profile>(source).ptr();
-      Extension* extension = Details<Extension>(details).ptr();
+      const Extension* extension = Details<const Extension>(details).ptr();
       // The ExtensionPrefStore for the local state watches all profiles.
       if (profile_ == NULL || profile_ == extension_profile)
         UninstallExtension(extension);
@@ -190,7 +190,7 @@ void ExtensionPrefStore::Observe(NotificationType type,
   }
 }
 
-ExtensionPrefStore::ExtensionPrefs::ExtensionPrefs(Extension* extension,
+ExtensionPrefStore::ExtensionPrefs::ExtensionPrefs(const Extension* extension,
     PrefValueMap* values) : extension(extension), pref_values(values) {}
 
 ExtensionPrefStore::ExtensionPrefs::~ExtensionPrefs() {
diff --git a/chrome/browser/extensions/extension_pref_store.h b/chrome/browser/extensions/extension_pref_store.h
index 926f29e..00248c3 100644
--- a/chrome/browser/extensions/extension_pref_store.h
+++ b/chrome/browser/extensions/extension_pref_store.h
@@ -39,13 +39,13 @@ class ExtensionPrefStore : public PrefStore,
   // Begins tracking the preference and value an extension wishes to set. This
   // must be called each time an extension API tries to set a preference.
   // The ExtensionPrefStore will take ownership of the |pref_value|.
-  virtual void InstallExtensionPref(Extension* extension,
+  virtual void InstallExtensionPref(const Extension* extension,
                                     const char* pref_path,
                                     Value* pref_value);
 
   // Removes an extension and all its preference settings from this PrefStore.
   // This must be called when an extension is uninstalled or disabled.
-  virtual void UninstallExtension(Extension* extension);
+  virtual void UninstallExtension(const Extension* extension);
 
   // PrefStore methods:
   virtual DictionaryValue* prefs() { return prefs_.get(); }
@@ -56,7 +56,7 @@ class ExtensionPrefStore : public PrefStore,
   // The nested pairs are <extension, <pref_path, pref_value> >. This is here,
   // rather than in (say) notification_type.h, to keep the dependency on
   // std::pair out of the many places that include notification_type.h.
-  typedef std::pair<Extension*, std::pair<const char*, Value*> >
+  typedef std::pair<const Extension*, std::pair<const char*, Value*> >
       ExtensionPrefDetails;
 
  protected:
@@ -95,10 +95,10 @@ class ExtensionPrefStore : public PrefStore,
 
   // Associates an extension with the prefs it sets. Owns the pref values.
   struct ExtensionPrefs {
-    ExtensionPrefs(Extension* extension, PrefValueMap* values);
+    ExtensionPrefs(const Extension* extension, PrefValueMap* values);
     ~ExtensionPrefs();
 
-    Extension* extension;
+    const Extension* extension;
     PrefValueMap* pref_values;
   };
 
diff --git a/chrome/browser/extensions/extension_prefs.cc b/chrome/browser/extensions/extension_prefs.cc
index eb6485f..8fbabf6 100644
--- a/chrome/browser/extensions/extension_prefs.cc
+++ b/chrome/browser/extensions/extension_prefs.cc
@@ -320,7 +320,7 @@ bool ExtensionPrefs::DidExtensionEscalatePermissions(
 }
 
 void ExtensionPrefs::SetDidExtensionEscalatePermissions(
-    Extension* extension, bool did_escalate) {
+    const Extension* extension, bool did_escalate) {
   UpdateExtensionPref(extension->id(), kExtensionDidEscalatePermissions,
                       Value::CreateBooleanValue(did_escalate));
   prefs_->ScheduleSavePersistentPrefs();
@@ -518,7 +518,7 @@ void ExtensionPrefs::SetToolbarOrder(
 }
 
 void ExtensionPrefs::OnExtensionInstalled(
-    Extension* extension, Extension::State initial_state,
+    const Extension* extension, Extension::State initial_state,
     bool initial_incognito_enabled) {
   const std::string& id = extension->id();
   UpdateExtensionPref(id, kPrefState,
@@ -575,7 +575,7 @@ Extension::State ExtensionPrefs::GetExtensionState(
   return static_cast<Extension::State>(state);
 }
 
-void ExtensionPrefs::SetExtensionState(Extension* extension,
+void ExtensionPrefs::SetExtensionState(const Extension* extension,
                                        Extension::State state) {
   UpdateExtensionPref(extension->id(), kPrefState,
                       Value::CreateIntegerValue(state));
@@ -596,7 +596,7 @@ std::string ExtensionPrefs::GetVersionString(const std::string& extension_id) {
   return version;
 }
 
-void ExtensionPrefs::UpdateManifest(Extension* extension) {
+void ExtensionPrefs::UpdateManifest(const Extension* extension) {
   if (extension->location() != Extension::LOAD) {
     UpdateExtensionPref(extension->id(), kPrefManifest,
                         extension->manifest_value()->DeepCopy());
diff --git a/chrome/browser/extensions/extension_prefs.h b/chrome/browser/extensions/extension_prefs.h
index 97547ea..eb16329 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -63,7 +63,7 @@ class ExtensionPrefs {
   void SetToolbarOrder(const std::vector<std::string>& extension_ids);
 
   // Called when an extension is installed, so that prefs get created.
-  void OnExtensionInstalled(Extension* extension,
+  void OnExtensionInstalled(const Extension* extension,
                             Extension::State initial_state,
                             bool initial_incognito_enabled);
 
@@ -76,14 +76,14 @@ class ExtensionPrefs {
   Extension::State GetExtensionState(const std::string& extension_id);
 
   // Called to change the extension's state when it is enabled/disabled.
-  void SetExtensionState(Extension* extension, Extension::State);
+  void SetExtensionState(const Extension* extension, Extension::State);
 
   // Did the extension ask to escalate its permission during an upgrade?
   bool DidExtensionEscalatePermissions(const std::string& id);
 
   // If |did_escalate| is true, the preferences for |extension| will be set to
   // require the install warning when the user tries to enable.
-  void SetDidExtensionEscalatePermissions(Extension* extension,
+  void SetDidExtensionEscalatePermissions(const Extension* extension,
                                           bool did_escalate);
 
   // Returns the version string for the currently installed extension, or
@@ -92,7 +92,7 @@ class ExtensionPrefs {
 
   // Re-writes the extension manifest into the prefs.
   // Called to change the extension's manifest when it's re-localized.
-  void UpdateManifest(Extension* extension);
+  void UpdateManifest(const Extension* extension);
 
   // Returns extension path based on extension ID, or empty FilePath on error.
   FilePath GetExtensionPath(const std::string& extension_id);
diff --git a/chrome/browser/extensions/extension_process_manager.cc b/chrome/browser/extensions/extension_process_manager.cc
index f941544..12ff5c0 100644
--- a/chrome/browser/extensions/extension_process_manager.cc
+++ b/chrome/browser/extensions/extension_process_manager.cc
@@ -32,11 +32,12 @@ class IncognitoExtensionProcessManager : public ExtensionProcessManager {
  public:
   explicit IncognitoExtensionProcessManager(Profile* profile);
   virtual ~IncognitoExtensionProcessManager() {}
-  virtual ExtensionHost* CreateView(Extension* extension,
+  virtual ExtensionHost* CreateView(const Extension* extension,
                                     const GURL& url,
                                     Browser* browser,
                                     ViewType::Type view_type);
-  virtual void CreateBackgroundHost(Extension* extension, const GURL& url);
+  virtual void CreateBackgroundHost(const Extension* extension,
+                                    const GURL& url);
   virtual SiteInstance* GetSiteInstanceForURL(const GURL& url);
   virtual RenderProcessHost* GetExtensionProcess(const GURL& url);
 
@@ -48,7 +49,7 @@ class IncognitoExtensionProcessManager : public ExtensionProcessManager {
 
   // Returns the extension for an URL, which can either be a chrome-extension
   // URL or a web app URL.
-  Extension* GetExtensionOrAppByURL(const GURL& url);
+  const Extension* GetExtensionOrAppByURL(const GURL& url);
 
   // Returns true if the extension is allowed to run in incognito mode.
   bool IsIncognitoEnabled(const Extension* extension);
@@ -57,7 +58,7 @@ class IncognitoExtensionProcessManager : public ExtensionProcessManager {
 };
 
 static void CreateBackgroundHost(
-    ExtensionProcessManager* manager, Extension* extension) {
+    ExtensionProcessManager* manager, const Extension* extension) {
   // Start the process for the master page, if it exists.
   if (extension->background_url().is_valid())
     manager->CreateBackgroundHost(extension, extension->background_url());
@@ -110,7 +111,7 @@ ExtensionProcessManager::~ExtensionProcessManager() {
   DCHECK(background_hosts_.empty());
 }
 
-ExtensionHost* ExtensionProcessManager::CreateView(Extension* extension,
+ExtensionHost* ExtensionProcessManager::CreateView(const Extension* extension,
                                                    const GURL& url,
                                                    Browser* browser,
                                                    ViewType::Type view_type) {
@@ -137,14 +138,14 @@ ExtensionHost* ExtensionProcessManager::CreateView(const GURL& url,
   ExtensionsService* service =
       browsing_instance_->profile()->GetExtensionsService();
   if (service) {
-    Extension* extension = service->GetExtensionByURL(url);
+    const Extension* extension = service->GetExtensionByURL(url);
     if (extension)
       return CreateView(extension, url, browser, view_type);
   }
   return NULL;
 }
 
-ExtensionHost* ExtensionProcessManager::CreatePopup(Extension* extension,
+ExtensionHost* ExtensionProcessManager::CreatePopup(const Extension* extension,
                                                     const GURL& url,
                                                     Browser* browser) {
   return CreateView(extension, url, browser, ViewType::EXTENSION_POPUP);
@@ -155,9 +156,8 @@ ExtensionHost* ExtensionProcessManager::CreatePopup(const GURL& url,
   return CreateView(url, browser, ViewType::EXTENSION_POPUP);
 }
 
-ExtensionHost* ExtensionProcessManager::CreateInfobar(Extension* extension,
-                                                      const GURL& url,
-                                                      Browser* browser) {
+ExtensionHost* ExtensionProcessManager::CreateInfobar(
+    const Extension* extension, const GURL& url, Browser* browser) {
   return CreateView(extension, url, browser, ViewType::EXTENSION_INFOBAR);
 }
 
@@ -167,7 +167,7 @@ ExtensionHost* ExtensionProcessManager::CreateInfobar(const GURL& url,
 }
 
 void ExtensionProcessManager::CreateBackgroundHost(
-    Extension* extension, const GURL& url) {
+    const Extension* extension, const GURL& url) {
   // Don't create multiple background hosts for an extension.
   if (GetBackgroundHostForExtension(extension))
     return;
@@ -185,7 +185,7 @@ void ExtensionProcessManager::CreateBackgroundHost(
   OnExtensionHostCreated(host, true);
 }
 
-void ExtensionProcessManager::OpenOptionsPage(Extension* extension,
+void ExtensionProcessManager::OpenOptionsPage(const Extension* extension,
                                               Browser* browser) {
   DCHECK(!extension->options_url().is_empty());
 
@@ -203,7 +203,7 @@ void ExtensionProcessManager::OpenOptionsPage(Extension* extension,
 }
 
 ExtensionHost* ExtensionProcessManager::GetBackgroundHostForExtension(
-    Extension* extension) {
+    const Extension* extension) {
   for (ExtensionHostSet::iterator iter = background_hosts_.begin();
        iter != background_hosts_.end(); ++iter) {
     ExtensionHost* host = *iter;
@@ -230,7 +230,7 @@ void ExtensionProcessManager::RegisterExtensionProcess(
       browsing_instance_->profile()->GetExtensionsService();
 
   std::vector<std::string> page_action_ids;
-  Extension* extension =
+  const Extension* extension =
       extension_service->GetExtensionById(extension_id, false);
   if (extension->page_action())
     page_action_ids.push_back(extension->page_action()->id());
@@ -288,14 +288,14 @@ void ExtensionProcessManager::Observe(NotificationType type,
       ExtensionsService* service =
           Source<Profile>(source).ptr()->GetExtensionsService();
       if (service->is_ready()) {
-        Extension* extension = Details<Extension>(details).ptr();
+        const Extension* extension = Details<const Extension>(details).ptr();
         ::CreateBackgroundHost(this, extension);
       }
       break;
     }
 
     case NotificationType::EXTENSION_UNLOADED: {
-      Extension* extension = Details<Extension>(details).ptr();
+      const Extension* extension = Details<const Extension>(details).ptr();
       for (ExtensionHostSet::iterator iter = background_hosts_.begin();
            iter != background_hosts_.end(); ++iter) {
         ExtensionHost* host = *iter;
@@ -374,7 +374,7 @@ IncognitoExtensionProcessManager::IncognitoExtensionProcessManager(
 }
 
 ExtensionHost* IncognitoExtensionProcessManager::CreateView(
-    Extension* extension,
+    const Extension* extension,
     const GURL& url,
     Browser* browser,
     ViewType::Type view_type) {
@@ -394,7 +394,7 @@ ExtensionHost* IncognitoExtensionProcessManager::CreateView(
 }
 
 void IncognitoExtensionProcessManager::CreateBackgroundHost(
-    Extension* extension, const GURL& url) {
+    const Extension* extension, const GURL& url) {
   if (extension->incognito_split_mode()) {
     if (IsIncognitoEnabled(extension))
       ExtensionProcessManager::CreateBackgroundHost(extension, url);
@@ -406,7 +406,7 @@ void IncognitoExtensionProcessManager::CreateBackgroundHost(
 
 SiteInstance* IncognitoExtensionProcessManager::GetSiteInstanceForURL(
     const GURL& url) {
-  Extension* extension = GetExtensionOrAppByURL(url);
+  const Extension* extension = GetExtensionOrAppByURL(url);
   if (!extension || extension->incognito_split_mode()) {
     return ExtensionProcessManager::GetSiteInstanceForURL(url);
   } else {
@@ -416,7 +416,7 @@ SiteInstance* IncognitoExtensionProcessManager::GetSiteInstanceForURL(
 
 RenderProcessHost* IncognitoExtensionProcessManager::GetExtensionProcess(
     const GURL& url) {
-  Extension* extension = GetExtensionOrAppByURL(url);
+  const Extension* extension = GetExtensionOrAppByURL(url);
   if (!extension || extension->incognito_split_mode()) {
     return ExtensionProcessManager::GetExtensionProcess(url);
   } else {
@@ -424,7 +424,7 @@ RenderProcessHost* IncognitoExtensionProcessManager::GetExtensionProcess(
   }
 }
 
-Extension* IncognitoExtensionProcessManager::GetExtensionOrAppByURL(
+const Extension* IncognitoExtensionProcessManager::GetExtensionOrAppByURL(
     const GURL& url) {
   ExtensionsService* service =
       browsing_instance_->profile()->GetExtensionsService();
diff --git a/chrome/browser/extensions/extension_process_manager.h b/chrome/browser/extensions/extension_process_manager.h
index d284275..2d812ef 100644
--- a/chrome/browser/extensions/extension_process_manager.h
+++ b/chrome/browser/extensions/extension_process_manager.h
@@ -35,33 +35,34 @@ class ExtensionProcessManager : public NotificationObserver {
   // Creates a new ExtensionHost with its associated view, grouping it in the
   // appropriate SiteInstance (and therefore process) based on the URL and
   // profile.
-  virtual ExtensionHost* CreateView(Extension* extension,
+  virtual ExtensionHost* CreateView(const Extension* extension,
                             const GURL& url,
                             Browser* browser,
                             ViewType::Type view_type);
   ExtensionHost* CreateView(const GURL& url,
                             Browser* browser,
                             ViewType::Type view_type);
-  ExtensionHost* CreatePopup(Extension* extension,
+  ExtensionHost* CreatePopup(const Extension* extension,
                              const GURL& url,
                              Browser* browser);
   ExtensionHost* CreatePopup(const GURL& url, Browser* browser);
-  ExtensionHost* CreateInfobar(Extension* extension,
+  ExtensionHost* CreateInfobar(const Extension* extension,
                                const GURL& url,
                                Browser* browser);
   ExtensionHost* CreateInfobar(const GURL& url,
                                Browser* browser);
 
   // Open the extension's options page.
-  void OpenOptionsPage(Extension* extension, Browser* browser);
+  void OpenOptionsPage(const Extension* extension, Browser* browser);
 
   // Creates a new UI-less extension instance.  Like CreateView, but not
   // displayed anywhere.
-  virtual void CreateBackgroundHost(Extension* extension, const GURL& url);
+  virtual void CreateBackgroundHost(const Extension* extension,
+                                    const GURL& url);
 
   // Gets the ExtensionHost for the background page for an extension, or NULL if
   // the extension isn't running or doesn't have a background page.
-  ExtensionHost* GetBackgroundHostForExtension(Extension* extension);
+  ExtensionHost* GetBackgroundHostForExtension(const Extension* extension);
 
   // Returns the SiteInstance that the given URL belongs to.
   virtual SiteInstance* GetSiteInstanceForURL(const GURL& url);
diff --git a/chrome/browser/extensions/extension_proxy_apitest.cc b/chrome/browser/extensions/extension_proxy_apitest.cc
index 9c127ad..a22baf8 100644
--- a/chrome/browser/extensions/extension_proxy_apitest.cc
+++ b/chrome/browser/extensions/extension_proxy_apitest.cc
@@ -16,7 +16,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, ProxyAutoSettings) {
       switches::kEnableExperimentalExtensionApis);
 
   ASSERT_TRUE(RunExtensionTest("proxy/auto")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension);
 
   PrefService* pref_service = browser()->profile()->GetPrefs();
@@ -46,7 +46,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, ProxyManualSingle) {
       switches::kEnableExperimentalExtensionApis);
 
   ASSERT_TRUE(RunExtensionTest("proxy/single")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension);
 
   PrefService* pref_service = browser()->profile()->GetPrefs();
@@ -81,7 +81,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, ProxyManualIndividual) {
       switches::kEnableExperimentalExtensionApis);
 
   ASSERT_TRUE(RunExtensionTest("proxy/individual")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension);
 
   PrefService* pref_service = browser()->profile()->GetPrefs();
diff --git a/chrome/browser/extensions/extension_sidebar_api.cc b/chrome/browser/extensions/extension_sidebar_api.cc
index 8b6913e..7dbb6fd 100644
--- a/chrome/browser/extensions/extension_sidebar_api.cc
+++ b/chrome/browser/extensions/extension_sidebar_api.cc
@@ -51,7 +51,7 @@ const char kShownState[] = "shown";
 }
 
 static GURL ResolvePossiblyRelativeURL(const std::string& url_string,
-                                       Extension* extension) {
+                                       const Extension* extension) {
   GURL url = GURL(url_string);
   if (!url.is_valid())
     url = extension->GetResourceURL(url_string);
@@ -59,7 +59,7 @@ static GURL ResolvePossiblyRelativeURL(const std::string& url_string,
   return url;
 }
 
-static bool CanUseHost(Extension* extension,
+static bool CanUseHost(const Extension* extension,
                        const GURL& url,
                        std::string* error) {
   if (extension->HasHostPermission(url))
diff --git a/chrome/browser/extensions/extension_tabs_module.cc b/chrome/browser/extensions/extension_tabs_module.cc
index 76b001a..ce3a92a 100644
--- a/chrome/browser/extensions/extension_tabs_module.cc
+++ b/chrome/browser/extensions/extension_tabs_module.cc
@@ -65,7 +65,7 @@ static bool GetTabById(int tab_id, Profile* profile,
 // but because the api shipped with urls resolved relative to their extension
 // base, we decided it wasn't worth breaking existing extensions to fix.
 static GURL ResolvePossiblyRelativeURL(std::string url_string,
-                                       Extension* extension);
+                                       const Extension* extension);
 
 // Return the type name for a browser window type.
 static std::string GetWindowTypeText(Browser::Type type);
@@ -705,7 +705,7 @@ bool UpdateTabFunction::RunImpl() {
     // JavaScript URLs can do the same kinds of things as cross-origin XHR, so
     // we need to check host permissions before allowing them.
     if (url.SchemeIs(chrome::kJavaScriptScheme)) {
-      Extension* extension = GetExtension();
+      const Extension* extension = GetExtension();
       const std::vector<URLPattern> host_permissions =
           extension->host_permissions();
       if (!Extension::CanExecuteScriptOnPage(
@@ -1149,7 +1149,7 @@ static std::string GetWindowTypeText(Browser::Type type) {
 }
 
 static GURL ResolvePossiblyRelativeURL(std::string url_string,
-                                       Extension* extension) {
+                                       const Extension* extension) {
   GURL url = GURL(url_string);
   if (!url.is_valid())
     url = extension->GetResourceURL(url_string);
diff --git a/chrome/browser/extensions/extension_toolbar_model.cc b/chrome/browser/extensions/extension_toolbar_model.cc
index 086b8c4..4b55442 100644
--- a/chrome/browser/extensions/extension_toolbar_model.cc
+++ b/chrome/browser/extensions/extension_toolbar_model.cc
@@ -45,7 +45,7 @@ void ExtensionToolbarModel::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
-void ExtensionToolbarModel::MoveBrowserAction(Extension* extension,
+void ExtensionToolbarModel::MoveBrowserAction(const Extension* extension,
                                               int index) {
   ExtensionList::iterator pos = std::find(begin(), end(), extension);
   if (pos == end()) {
@@ -93,7 +93,7 @@ void ExtensionToolbarModel::Observe(NotificationType type,
   if (!service_->is_ready())
     return;
 
-  Extension* extension = Details<Extension>(details).ptr();
+  const Extension* extension = Details<const Extension>(details).ptr();
   if (type == NotificationType::EXTENSION_LOADED) {
     AddExtension(extension);
   } else if (type == NotificationType::EXTENSION_UNLOADED ||
@@ -104,7 +104,7 @@ void ExtensionToolbarModel::Observe(NotificationType type,
   }
 }
 
-void ExtensionToolbarModel::AddExtension(Extension* extension) {
+void ExtensionToolbarModel::AddExtension(const Extension* extension) {
   // We only care about extensions with browser actions.
   if (!extension->browser_action())
     return;
@@ -126,7 +126,7 @@ void ExtensionToolbarModel::AddExtension(Extension* extension) {
   UpdatePrefs();
 }
 
-void ExtensionToolbarModel::RemoveExtension(Extension* extension) {
+void ExtensionToolbarModel::RemoveExtension(const Extension* extension) {
   ExtensionList::iterator pos = std::find(begin(), end(), extension);
   if (pos == end()) {
     return;
@@ -162,7 +162,7 @@ void ExtensionToolbarModel::InitializeExtensionList() {
 
   // Create the lists.
   for (size_t i = 0; i < service_->extensions()->size(); ++i) {
-    Extension* extension = service_->extensions()->at(i);
+    const Extension* extension = service_->extensions()->at(i);
     if (!extension->browser_action())
       continue;
 
@@ -208,7 +208,7 @@ void ExtensionToolbarModel::UpdatePrefs() {
   service_->extension_prefs()->SetToolbarOrder(ids);
 }
 
-Extension* ExtensionToolbarModel::GetExtensionByIndex(int index) const {
+const Extension* ExtensionToolbarModel::GetExtensionByIndex(int index) const {
   return toolitems_.at(index);
 }
 
diff --git a/chrome/browser/extensions/extension_toolbar_model.h b/chrome/browser/extensions/extension_toolbar_model.h
index a38fc8c..37c3a08 100644
--- a/chrome/browser/extensions/extension_toolbar_model.h
+++ b/chrome/browser/extensions/extension_toolbar_model.h
@@ -30,13 +30,13 @@ class ExtensionToolbarModel : public NotificationObserver {
    public:
     // An extension with a browser action button has been added, and should go
     // in the toolbar at |index|.
-    virtual void BrowserActionAdded(Extension* extension, int index) {}
+    virtual void BrowserActionAdded(const Extension* extension, int index) {}
 
     // The browser action button for |extension| should no longer show.
-    virtual void BrowserActionRemoved(Extension* extension) {}
+    virtual void BrowserActionRemoved(const Extension* extension) {}
 
     // The browser action button for |extension| has been moved to |index|.
-    virtual void BrowserActionMoved(Extension* extension, int index) {}
+    virtual void BrowserActionMoved(const Extension* extension, int index) {}
 
     // Called when the model has finished loading.
     virtual void ModelLoaded() {}
@@ -48,7 +48,7 @@ class ExtensionToolbarModel : public NotificationObserver {
   // Functions called by the view.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
-  void MoveBrowserAction(Extension* extension, int index);
+  void MoveBrowserAction(const Extension* extension, int index);
   // If count == size(), this will set the visible icon count to -1, meaning
   // "show all actions".
   void SetVisibleIconCount(int count);
@@ -69,7 +69,7 @@ class ExtensionToolbarModel : public NotificationObserver {
     return toolitems_.end();
   }
 
-  Extension* GetExtensionByIndex(int index) const;
+  const Extension* GetExtensionByIndex(int index) const;
 
   // Utility functions for converting between an index into the list of
   // incognito-enabled browser actions, and the list of all browser actions.
@@ -93,8 +93,8 @@ class ExtensionToolbarModel : public NotificationObserver {
   // Our observers.
   ObserverList<Observer> observers_;
 
-  void AddExtension(Extension* extension);
-  void RemoveExtension(Extension* extension);
+  void AddExtension(const Extension* extension);
+  void RemoveExtension(const Extension* extension);
 
   // Our ExtensionsService, guaranteed to outlive us.
   ExtensionsService* service_;
diff --git a/chrome/browser/extensions/extension_toolbar_model_browsertest.cc b/chrome/browser/extensions/extension_toolbar_model_browsertest.cc
index 031672e..45c936e 100644
--- a/chrome/browser/extensions/extension_toolbar_model_browsertest.cc
+++ b/chrome/browser/extensions/extension_toolbar_model_browsertest.cc
@@ -37,19 +37,19 @@ class ExtensionToolbarModelTest : public ExtensionBrowserTest,
     model_->RemoveObserver(this);
   }
 
-  virtual void BrowserActionAdded(Extension* extension, int index) {
+  virtual void BrowserActionAdded(const Extension* extension, int index) {
     inserted_count_++;
   }
 
-  virtual void BrowserActionRemoved(Extension* extension) {
+  virtual void BrowserActionRemoved(const Extension* extension) {
     removed_count_++;
   }
 
-  virtual void BrowserActionMoved(Extension* extension, int index) {
+  virtual void BrowserActionMoved(const Extension* extension, int index) {
     moved_count_++;
   }
 
-  Extension* ExtensionAt(int index) {
+  const Extension* ExtensionAt(int index) {
     for (ExtensionList::iterator i = model_->begin(); i < model_->end(); ++i) {
       if (index-- == 0)
         return *i;
@@ -87,7 +87,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionToolbarModelTest, Basic) {
   // We should now find our extension in the model.
   EXPECT_EQ(1, inserted_count_);
   EXPECT_EQ(1u, model_->size());
-  Extension* extension = ExtensionAt(0);
+  const Extension* extension = ExtensionAt(0);
   ASSERT_TRUE(NULL != extension);
   EXPECT_STREQ("A browser action with no icon that makes the page red",
                extension->name().c_str());
@@ -96,7 +96,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionToolbarModelTest, Basic) {
   model_->MoveBrowserAction(extension, 0);
   EXPECT_EQ(1, moved_count_);
   EXPECT_EQ(1u, model_->size());
-  Extension* extension2 = ExtensionAt(0);
+  const Extension* extension2 = ExtensionAt(0);
   EXPECT_EQ(extension, extension2);
 
   UnloadExtension(extension->id());
@@ -118,7 +118,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionToolbarModelTest, ReorderAndReinsert) {
   // First extension loaded.
   EXPECT_EQ(1, inserted_count_);
   EXPECT_EQ(1u, model_->size());
-  Extension* extensionA = ExtensionAt(0);
+  const Extension* extensionA = ExtensionAt(0);
   ASSERT_TRUE(NULL != extensionA);
   EXPECT_STREQ("A browser action with no icon that makes the page red",
                extensionA->name().c_str());
@@ -132,7 +132,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionToolbarModelTest, ReorderAndReinsert) {
   // Second extension loaded.
   EXPECT_EQ(2, inserted_count_);
   EXPECT_EQ(2u, model_->size());
-  Extension* extensionB = ExtensionAt(1);
+  const Extension* extensionB = ExtensionAt(1);
   ASSERT_TRUE(NULL != extensionB);
   EXPECT_STREQ("Popup tester", extensionB->name().c_str());
 
@@ -145,7 +145,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionToolbarModelTest, ReorderAndReinsert) {
   // Third extension loaded.
   EXPECT_EQ(3, inserted_count_);
   EXPECT_EQ(3u, model_->size());
-  Extension* extensionC = ExtensionAt(2);
+  const Extension* extensionC = ExtensionAt(2);
   ASSERT_TRUE(NULL != extensionC);
   EXPECT_STREQ("A page action which removes a popup.",
                extensionC->name().c_str());
diff --git a/chrome/browser/extensions/extension_updater.cc b/chrome/browser/extensions/extension_updater.cc
index abdba15..df19489 100644
--- a/chrome/browser/extensions/extension_updater.cc
+++ b/chrome/browser/extensions/extension_updater.cc
@@ -734,7 +734,7 @@ bool ExtensionUpdater::GetExistingVersion(const std::string& id,
     *version = prefs_->GetString(kExtensionBlacklistUpdateVersion);
     return true;
   }
-  Extension* extension = service_->GetExtensionById(id, false);
+  const Extension* extension = service_->GetExtensionById(id, false);
   if (!extension) {
     return false;
   }
diff --git a/chrome/browser/extensions/extension_updater_unittest.cc b/chrome/browser/extensions/extension_updater_unittest.cc
index bae09c6..581be2b 100644
--- a/chrome/browser/extensions/extension_updater_unittest.cc
+++ b/chrome/browser/extensions/extension_updater_unittest.cc
@@ -57,7 +57,7 @@ class MockService : public ExtensionUpdateService {
     FAIL();
   }
 
-  virtual Extension* GetExtensionById(const std::string& id, bool) {
+  virtual const Extension* GetExtensionById(const std::string& id, bool) {
     ADD_FAILURE();
     return NULL;
   }
@@ -142,7 +142,7 @@ class ServiceForManifestTests : public MockService {
 
   virtual ~ServiceForManifestTests() {}
 
-  virtual Extension* GetExtensionById(const std::string& id, bool) {
+  virtual const Extension* GetExtensionById(const std::string& id, bool) {
     for (ExtensionList::iterator iter = extensions_.begin();
         iter != extensions_.end(); ++iter) {
      if ((*iter)->id() == id) {
@@ -194,7 +194,7 @@ class ServiceForDownloadTests : public MockService {
     return pending_extensions_;
   }
 
-  virtual Extension* GetExtensionById(const std::string& id, bool) {
+  virtual const Extension* GetExtensionById(const std::string& id, bool) {
     last_inquired_extension_id_ = id;
     return NULL;
   }
@@ -803,7 +803,7 @@ class ExtensionUpdaterTest : public testing::Test {
     service.set_extensions(tmp);
 
     ManifestFetchData fetch_data(update_url);
-    Extension* extension = tmp[0];
+    const Extension* extension = tmp[0];
     fetch_data.AddExtension(extension->id(), extension->VersionString(),
                             ManifestFetchData::kNeverPinged);
     UpdateManifest::Results results;
diff --git a/chrome/browser/extensions/extension_webstore_private_api.cc b/chrome/browser/extensions/extension_webstore_private_api.cc
index 3471cd4..5744beb 100644
--- a/chrome/browser/extensions/extension_webstore_private_api.cc
+++ b/chrome/browser/extensions/extension_webstore_private_api.cc
@@ -53,7 +53,7 @@ BrowserSignin* GetBrowserSignin(Profile* profile) {
 
 bool IsWebStoreURL(Profile* profile, const GURL& url) {
   ExtensionsService* service = profile->GetExtensionsService();
-  Extension* store = service->GetWebStoreApp();
+  const Extension* store = service->GetWebStoreApp();
   DCHECK(store);
   return (service->GetExtensionByWebExtent(url) == store);
 }
diff --git a/chrome/browser/extensions/extensions_service.cc b/chrome/browser/extensions/extensions_service.cc
index f48445e..5c81670 100644
--- a/chrome/browser/extensions/extensions_service.cc
+++ b/chrome/browser/extensions/extensions_service.cc
@@ -94,7 +94,7 @@ bool ShouldReloadExtensionManifest(const ExtensionInfo& info) {
   return extension_l10n_util::ShouldRelocalizeManifest(info);
 }
 
-void GetExplicitOriginsInExtent(Extension* extension,
+void GetExplicitOriginsInExtent(const Extension* extension,
                                 std::vector<GURL>* origins) {
   typedef std::vector<URLPattern> PatternList;
   std::set<GURL> set;
@@ -224,7 +224,7 @@ class ExtensionsServiceBackend
   // Note: We take ownership of |extension|.
   void OnExtensionUnpacked(const FilePath& crx_path,
                            const FilePath& unpacked_path,
-                           Extension* extension,
+                           const Extension* extension,
                            const std::string expected_id);
 
   // Notify the frontend that there was an error loading an extension.
@@ -295,7 +295,7 @@ void ExtensionsServiceBackend::LoadSingleExtension(
   file_util::AbsolutePath(&extension_path);
 
   std::string error;
-  scoped_refptr<Extension> extension = extension_file_util::LoadExtension(
+  scoped_refptr<const Extension> extension = extension_file_util::LoadExtension(
       extension_path,
       Extension::LOAD,
       false,  // Don't require id
@@ -439,7 +439,7 @@ void ExtensionsServiceBackend::ReloadExtensionManifests(
 
     // We need to reload original manifest in order to localize properly.
     std::string error;
-    scoped_refptr<Extension> extension(extension_file_util::LoadExtension(
+    scoped_refptr<const Extension> extension(extension_file_util::LoadExtension(
         info->extension_path, info->extension_location, false, &error));
 
     if (extension.get())
@@ -469,9 +469,9 @@ bool ExtensionsService::IsDownloadFromGallery(const GURL& download_url,
     return true;
   }
 
-  Extension* download_extension = GetExtensionByWebExtent(download_url);
-  Extension* referrer_extension = GetExtensionByWebExtent(referrer_url);
-  Extension* webstore_app = GetWebStoreApp();
+  const Extension* download_extension = GetExtensionByWebExtent(download_url);
+  const Extension* referrer_extension = GetExtensionByWebExtent(referrer_url);
+  const Extension* webstore_app = GetWebStoreApp();
 
   bool referrer_valid = (referrer_extension == webstore_app);
   bool download_valid = (download_extension == webstore_app);
@@ -762,7 +762,7 @@ void ExtensionsService::AddPendingExtensionInternal(
 void ExtensionsService::ReloadExtension(const std::string& extension_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   FilePath path;
-  Extension* current_extension = GetExtensionById(extension_id, false);
+  const Extension* current_extension = GetExtensionById(extension_id, false);
 
   // Disable the extension if it's loaded. It might not be loaded if it crashed.
   if (current_extension) {
@@ -806,7 +806,8 @@ void ExtensionsService::UninstallExtension(const std::string& extension_id,
                                            bool external_uninstall) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  Extension* extension = GetExtensionByIdInternal(extension_id, true, true);
+  const Extension* extension =
+      GetExtensionByIdInternal(extension_id, true, true);
 
   // Callers should not send us nonexistent extensions.
   DCHECK(extension);
@@ -862,7 +863,8 @@ void ExtensionsService::ClearExtensionData(const GURL& extension_url) {
 void ExtensionsService::EnableExtension(const std::string& extension_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  Extension* extension = GetExtensionByIdInternal(extension_id, false, true);
+  const Extension* extension =
+      GetExtensionByIdInternal(extension_id, false, true);
   if (!extension) {
     return;
   }
@@ -886,7 +888,8 @@ void ExtensionsService::EnableExtension(const std::string& extension_id) {
 void ExtensionsService::DisableExtension(const std::string& extension_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  Extension* extension = GetExtensionByIdInternal(extension_id, true, false);
+  const Extension* extension =
+      GetExtensionByIdInternal(extension_id, true, false);
   // The extension may have been disabled already.
   if (!extension)
     return;
@@ -928,7 +931,7 @@ void ExtensionsService::LoadComponentExtensions() {
     }
 
     std::string error;
-    scoped_refptr<Extension> extension(Extension::Create(
+    scoped_refptr<const Extension> extension(Extension::Create(
         it->root_directory,
         Extension::COMPONENT,
         *static_cast<DictionaryValue*>(manifest.get()),
@@ -1068,7 +1071,7 @@ void ExtensionsService::ContinueLoadAllExtensions(
 void ExtensionsService::LoadInstalledExtension(const ExtensionInfo& info,
                                                bool write_to_prefs) {
   std::string error;
-  scoped_refptr<Extension> extension(NULL);
+  scoped_refptr<const Extension> extension(NULL);
   if (!extension_prefs_->IsExtensionAllowedByPolicy(info.extension_id)) {
     error = errors::kDisabledByPolicy;
   } else if (info.extension_manifest.get()) {
@@ -1104,7 +1107,7 @@ void ExtensionsService::LoadInstalledExtension(const ExtensionInfo& info,
   }
 }
 
-void ExtensionsService::NotifyExtensionLoaded(Extension* extension) {
+void ExtensionsService::NotifyExtensionLoaded(const Extension* extension) {
   // The ChromeURLRequestContexts need to be first to know that the extension
   // was loaded, otherwise a race can arise where a renderer that is created
   // for the extension may try to load an extension URL with an extension id
@@ -1127,14 +1130,14 @@ void ExtensionsService::NotifyExtensionLoaded(Extension* extension) {
   NotificationService::current()->Notify(
       NotificationType::EXTENSION_LOADED,
       Source<Profile>(profile_),
-      Details<Extension>(extension));
+      Details<const Extension>(extension));
 }
 
-void ExtensionsService::NotifyExtensionUnloaded(Extension* extension) {
+void ExtensionsService::NotifyExtensionUnloaded(const Extension* extension) {
   NotificationService::current()->Notify(
       NotificationType::EXTENSION_UNLOADED,
       Source<Profile>(profile_),
-      Details<Extension>(extension));
+      Details<const Extension>(extension));
 
   if (profile_) {
     profile_->UnregisterExtensionWithRequestContexts(extension);
@@ -1150,7 +1153,7 @@ void ExtensionsService::NotifyExtensionUnloaded(Extension* extension) {
   }
 }
 
-void ExtensionsService::GrantProtectedStorage(Extension* extension) {
+void ExtensionsService::GrantProtectedStorage(const Extension* extension) {
   DCHECK(extension->is_app()) << "Only Apps are allowed protected storage.";
   std::vector<GURL> origins;
   GetExplicitOriginsInExtent(extension, &origins);
@@ -1158,7 +1161,7 @@ void ExtensionsService::GrantProtectedStorage(Extension* extension) {
     ++protected_storage_map_[origins[i]];
 }
 
-void ExtensionsService::RevokeProtectedStorage(Extension* extension) {
+void ExtensionsService::RevokeProtectedStorage(const Extension* extension) {
   DCHECK(extension->is_app()) << "Attempting to revoke protected storage from "
       << " a non-app extension.";
   std::vector<GURL> origins;
@@ -1171,7 +1174,7 @@ void ExtensionsService::RevokeProtectedStorage(Extension* extension) {
   }
 }
 
-void ExtensionsService::GrantUnlimitedStorage(Extension* extension) {
+void ExtensionsService::GrantUnlimitedStorage(const Extension* extension) {
   DCHECK(extension->HasApiPermission(Extension::kUnlimitedStoragePermission));
   std::vector<GURL> origins;
   GetExplicitOriginsInExtent(extension, &origins);
@@ -1206,7 +1209,7 @@ void ExtensionsService::GrantUnlimitedStorage(Extension* extension) {
   }
 }
 
-void ExtensionsService::RevokeUnlimitedStorage(Extension* extension) {
+void ExtensionsService::RevokeUnlimitedStorage(const Extension* extension) {
   DCHECK(extension->HasApiPermission(Extension::kUnlimitedStoragePermission));
   std::vector<GURL> origins;
   GetExplicitOriginsInExtent(extension, &origins);
@@ -1255,7 +1258,7 @@ void ExtensionsService::UpdateExtensionBlacklist(
   // Loop current extensions, unload installed extensions.
   for (ExtensionList::const_iterator iter = extensions_.begin();
        iter != extensions_.end(); ++iter) {
-    Extension* extension = (*iter);
+    const Extension* extension = (*iter);
     if (blacklist_set.find(extension->id()) != blacklist_set.end()) {
       to_be_removed.push_back(extension->id());
     }
@@ -1279,7 +1282,7 @@ void ExtensionsService::CheckAdminBlacklist() {
   // Loop through extensions list, unload installed extensions.
   for (ExtensionList::const_iterator iter = extensions_.begin();
        iter != extensions_.end(); ++iter) {
-    Extension* extension = (*iter);
+    const Extension* extension = (*iter);
     if (!extension_prefs_->IsExtensionAllowedByPolicy(extension->id()))
       to_be_removed.push_back(extension->id());
   }
@@ -1300,7 +1303,7 @@ bool ExtensionsService::IsIncognitoEnabled(const Extension* extension) {
   return extension_prefs_->IsIncognitoEnabled(extension->id());
 }
 
-void ExtensionsService::SetIsIncognitoEnabled(Extension* extension,
+void ExtensionsService::SetIsIncognitoEnabled(const Extension* extension,
                                               bool enabled) {
   extension_prefs_->SetIsIncognitoEnabled(extension->id(), enabled);
 
@@ -1320,12 +1323,13 @@ bool ExtensionsService::AllowFileAccess(const Extension* extension) {
           extension_prefs_->AllowFileAccess(extension->id()));
 }
 
-void ExtensionsService::SetAllowFileAccess(Extension* extension, bool allow) {
+void ExtensionsService::SetAllowFileAccess(const Extension* extension,
+                                           bool allow) {
   extension_prefs_->SetAllowFileAccess(extension->id(), allow);
   NotificationService::current()->Notify(
       NotificationType::EXTENSION_USER_SCRIPTS_UPDATED,
       Source<Profile>(profile_),
-      Details<Extension>(extension));
+      Details<const Extension>(extension));
 }
 
 void ExtensionsService::CheckForExternalUpdates() {
@@ -1343,7 +1347,7 @@ void ExtensionsService::CheckForExternalUpdates() {
 
 void ExtensionsService::UnloadExtension(const std::string& extension_id) {
   // Make sure the extension gets deleted after we return from this function.
-  scoped_refptr<Extension> extension(
+  scoped_refptr<const Extension> extension(
       GetExtensionByIdInternal(extension_id, true, true));
 
   // Callers should not send us nonexistent extensions.
@@ -1367,7 +1371,7 @@ void ExtensionsService::UnloadExtension(const std::string& extension_id) {
     NotificationService::current()->Notify(
         NotificationType::EXTENSION_UNLOADED_DISABLED,
         Source<Profile>(profile_),
-        Details<Extension>(extension.get()));
+        Details<const Extension>(extension.get()));
     return;
   }
 
@@ -1423,10 +1427,10 @@ void ExtensionsService::OnLoadedInstalledExtensions() {
       NotificationService::NoDetails());
 }
 
-void ExtensionsService::OnExtensionLoaded(Extension* extension,
+void ExtensionsService::OnExtensionLoaded(const Extension* extension,
                                           bool allow_privilege_increase) {
   // Ensure extension is deleted unless we transfer ownership.
-  scoped_refptr<Extension> scoped_extension(extension);
+  scoped_refptr<const Extension> scoped_extension(extension);
 
   // The extension is now loaded, remove its data from unloaded extension map.
   unloaded_extension_paths_.erase(extension->id());
@@ -1442,7 +1446,8 @@ void ExtensionsService::OnExtensionLoaded(Extension* extension,
       extension->location() == Extension::LOAD ||
       extension->location() == Extension::COMPONENT ||
       Extension::IsExternalLocation(extension->location())) {
-    Extension* old = GetExtensionByIdInternal(extension->id(), true, true);
+    const Extension* old = GetExtensionByIdInternal(extension->id(),
+                                                    true, true);
     if (old) {
       // CrxInstaller should have guaranteed that we aren't downgrading.
       CHECK(extension->version()->CompareTo(*(old->version())) >= 0);
@@ -1485,7 +1490,7 @@ void ExtensionsService::OnExtensionLoaded(Extension* extension,
         NotificationService::current()->Notify(
             NotificationType::EXTENSION_UPDATE_DISABLED,
             Source<Profile>(profile_),
-            Details<Extension>(extension));
+            Details<const Extension>(extension));
         break;
       default:
         NOTREACHED();
@@ -1518,12 +1523,12 @@ void ExtensionsService::UpdateActiveExtensionsInCrashReporter() {
   child_process_logging::SetActiveExtensions(extension_ids);
 }
 
-void ExtensionsService::OnExtensionInstalled(Extension* extension,
+void ExtensionsService::OnExtensionInstalled(const Extension* extension,
                                              bool allow_privilege_increase) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // Ensure extension is deleted unless we transfer ownership.
-  scoped_refptr<Extension> scoped_extension(extension);
+  scoped_refptr<const Extension> scoped_extension(extension);
   Extension::State initial_state = Extension::DISABLED;
   bool initial_enable_incognito = false;
   PendingExtensionMap::iterator it =
@@ -1645,12 +1650,12 @@ void ExtensionsService::OnExtensionInstalled(Extension* extension,
     NotificationService::current()->Notify(
         NotificationType::THEME_INSTALLED,
         Source<Profile>(profile_),
-        Details<Extension>(extension));
+        Details<const Extension>(extension));
   } else {
     NotificationService::current()->Notify(
         NotificationType::EXTENSION_INSTALLED,
         Source<Profile>(profile_),
-        Details<Extension>(extension));
+        Details<const Extension>(extension));
   }
 
   if (extension->is_app()) {
@@ -1663,9 +1668,8 @@ void ExtensionsService::OnExtensionInstalled(Extension* extension,
   OnExtensionLoaded(scoped_extension, allow_privilege_increase);
 }
 
-Extension* ExtensionsService::GetExtensionByIdInternal(const std::string& id,
-                                                       bool include_enabled,
-                                                       bool include_disabled) {
+const Extension* ExtensionsService::GetExtensionByIdInternal(
+    const std::string& id, bool include_enabled, bool include_disabled) {
   std::string lowercase_id = StringToLowerASCII(id);
   if (include_enabled) {
     for (ExtensionList::const_iterator iter = extensions_.begin();
@@ -1684,16 +1688,16 @@ Extension* ExtensionsService::GetExtensionByIdInternal(const std::string& id,
   return NULL;
 }
 
-Extension* ExtensionsService::GetWebStoreApp() {
+const Extension* ExtensionsService::GetWebStoreApp() {
   return GetExtensionById(extension_misc::kWebStoreAppId, false);
 }
 
-Extension* ExtensionsService::GetExtensionByURL(const GURL& url) {
+const Extension* ExtensionsService::GetExtensionByURL(const GURL& url) {
   return url.scheme() != chrome::kExtensionScheme ? NULL :
       GetExtensionById(url.host(), false);
 }
 
-Extension* ExtensionsService::GetExtensionByWebExtent(const GURL& url) {
+const Extension* ExtensionsService::GetExtensionByWebExtent(const GURL& url) {
   for (size_t i = 0; i < extensions_.size(); ++i) {
     if (extensions_[i]->web_extent().ContainsURL(url))
       return extensions_[i];
@@ -1707,11 +1711,11 @@ bool ExtensionsService::ExtensionBindingsAllowed(const GURL& url) {
     return true;
 
   // Allow bindings for all component, hosted apps.
-  Extension* extension = GetExtensionByWebExtent(url);
+  const Extension* extension = GetExtensionByWebExtent(url);
   return (extension && extension->location() == Extension::COMPONENT);
 }
 
-Extension* ExtensionsService::GetExtensionByOverlappingWebExtent(
+const Extension* ExtensionsService::GetExtensionByOverlappingWebExtent(
     const ExtensionExtent& extent) {
   for (size_t i = 0; i < extensions_.size(); ++i) {
     if (extensions_[i]->web_extent().OverlapsWith(extent))
@@ -1757,7 +1761,7 @@ void ExtensionsService::OnExternalExtensionFileFound(
   // Before even bothering to unpack, check and see if we already have this
   // version. This is important because these extensions are going to get
   // installed on every startup.
-  Extension* existing = GetExtensionById(id, true);
+  const Extension* existing = GetExtensionById(id, true);
   scoped_ptr<Version> other(Version::GetVersionFromString(version));
   if (existing) {
     switch (existing->version()->CompareTo(*other)) {
diff --git a/chrome/browser/extensions/extensions_service.h b/chrome/browser/extensions/extensions_service.h
index c00c264..213471c 100644
--- a/chrome/browser/extensions/extensions_service.h
+++ b/chrome/browser/extensions/extensions_service.h
@@ -89,8 +89,8 @@ class ExtensionUpdateService {
   virtual const PendingExtensionMap& pending_extensions() const = 0;
   virtual void UpdateExtension(const std::string& id, const FilePath& path,
                                const GURL& download_url) = 0;
-  virtual Extension* GetExtensionById(const std::string& id,
-                                      bool include_disabled) = 0;
+  virtual const Extension* GetExtensionById(const std::string& id,
+                                            bool include_disabled) = 0;
   virtual void UpdateExtensionBlacklist(
     const std::vector<std::string>& blacklist) = 0;
   virtual void CheckAdminBlacklist() = 0;
@@ -179,11 +179,11 @@ class ExtensionsService
 
   // Whether this extension can run in an incognito window.
   bool IsIncognitoEnabled(const Extension* extension);
-  void SetIsIncognitoEnabled(Extension* extension, bool enabled);
+  void SetIsIncognitoEnabled(const Extension* extension, bool enabled);
 
   // Whether this extension can inject scripts into pages with file URLs.
   bool AllowFileAccess(const Extension* extension);
-  void SetAllowFileAccess(Extension* extension, bool allow);
+  void SetAllowFileAccess(const Extension* extension, bool allow);
 
   // Initialize and start all installed extensions.
   void Init();
@@ -192,7 +192,8 @@ class ExtensionsService
   void InitEventRouters();
 
   // Look up an extension by ID.
-  Extension* GetExtensionById(const std::string& id, bool include_disabled) {
+  const Extension* GetExtensionById(const std::string& id,
+                                    bool include_disabled) {
     return GetExtensionByIdInternal(id, true, include_disabled);
   }
 
@@ -285,18 +286,19 @@ class ExtensionsService
   void GarbageCollectExtensions();
 
   // The App that represents the web store.
-  Extension* GetWebStoreApp();
+  const Extension* GetWebStoreApp();
 
   // Lookup an extension by |url|.
-  Extension* GetExtensionByURL(const GURL& url);
+  const Extension* GetExtensionByURL(const GURL& url);
 
   // If there is an extension for the specified url it is returned. Otherwise
   // returns the extension whose web extent contains |url|.
-  Extension* GetExtensionByWebExtent(const GURL& url);
+  const Extension* GetExtensionByWebExtent(const GURL& url);
 
   // Returns an extension that contains any URL that overlaps with the given
   // extent, if one exists.
-  Extension* GetExtensionByOverlappingWebExtent(const ExtensionExtent& extent);
+  const Extension* GetExtensionByOverlappingWebExtent(
+      const ExtensionExtent& extent);
 
   // Returns true if |url| should get extension api bindings and be permitted
   // to make api calls. Note that this is independent of what extension
@@ -321,11 +323,11 @@ class ExtensionsService
   virtual void OnLoadedInstalledExtensions();
 
   // Called when an extension has been loaded.
-  void OnExtensionLoaded(Extension* extension,
+  void OnExtensionLoaded(const Extension* extension,
                          bool allow_privilege_increase);
 
   // Called by the backend when an extension has been installed.
-  void OnExtensionInstalled(Extension* extension,
+  void OnExtensionInstalled(const Extension* extension,
                             bool allow_privilege_increase);
 
   // Called by the backend when an external extension is found.
@@ -411,9 +413,9 @@ class ExtensionsService
 
   // Look up an extension by ID, optionally including either or both of enabled
   // and disabled extensions.
-  Extension* GetExtensionByIdInternal(const std::string& id,
-                                      bool include_enabled,
-                                      bool include_disabled);
+  const Extension* GetExtensionByIdInternal(const std::string& id,
+                                            bool include_enabled,
+                                            bool include_disabled);
 
   // Like AddPendingExtension() but assumes an extension with the same
   // id is not already installed.
@@ -425,10 +427,10 @@ class ExtensionsService
       Extension::Location install_source);
 
   // Handles sending notification that |extension| was loaded.
-  void NotifyExtensionLoaded(Extension* extension);
+  void NotifyExtensionLoaded(const Extension* extension);
 
   // Handles sending notification that |extension| was unloaded.
-  void NotifyExtensionUnloaded(Extension* extension);
+  void NotifyExtensionUnloaded(const Extension* extension);
 
   // Helper that updates the active extension list used for crash reporting.
   void UpdateActiveExtensionsInCrashReporter();
@@ -437,10 +439,10 @@ class ExtensionsService
   void LoadInstalledExtension(const ExtensionInfo& info, bool write_to_prefs);
 
   // Helper methods to configure the storage services accordingly.
-  void GrantProtectedStorage(Extension* extension);
-  void RevokeProtectedStorage(Extension* extension);
-  void GrantUnlimitedStorage(Extension* extension);
-  void RevokeUnlimitedStorage(Extension* extension);
+  void GrantProtectedStorage(const Extension* extension);
+  void RevokeProtectedStorage(const Extension* extension);
+  void GrantUnlimitedStorage(const Extension* extension);
+  void RevokeUnlimitedStorage(const Extension* extension);
 
   // The profile this ExtensionsService is part of.
   Profile* profile_;
diff --git a/chrome/browser/extensions/extensions_service_unittest.cc b/chrome/browser/extensions/extensions_service_unittest.cc
index 18210a9..bcb3f86 100644
--- a/chrome/browser/extensions/extensions_service_unittest.cc
+++ b/chrome/browser/extensions/extensions_service_unittest.cc
@@ -421,7 +421,7 @@ class ExtensionsServiceTest
                        const NotificationDetails& details) {
     switch (type.value) {
       case NotificationType::EXTENSION_LOADED: {
-        Extension* extension = Details<Extension>(details).ptr();
+        const Extension* extension = Details<const Extension>(details).ptr();
         loaded_.push_back(extension);
         // The tests rely on the errors being in a certain order, which can vary
         // depending on how filesystem iteration works.
@@ -430,7 +430,7 @@ class ExtensionsServiceTest
       }
 
       case NotificationType::EXTENSION_UNLOADED: {
-        Extension* e = Details<Extension>(details).ptr();
+        const Extension* e = Details<const Extension>(details).ptr();
         unloaded_id_ = e->id();
         ExtensionList::iterator i =
             std::find(loaded_.begin(), loaded_.end(), e);
@@ -443,7 +443,7 @@ class ExtensionsServiceTest
       }
       case NotificationType::EXTENSION_INSTALLED:
       case NotificationType::THEME_INSTALLED:
-        installed_ = Details<Extension>(details).ptr();
+        installed_ = Details<const Extension>(details).ptr();
         break;
 
       default:
@@ -678,7 +678,7 @@ class ExtensionsServiceTest
  protected:
   ExtensionList loaded_;
   std::string unloaded_id_;
-  Extension* installed_;
+  const Extension* installed_;
 
  private:
   NotificationRegistrar registrar_;
@@ -776,7 +776,7 @@ TEST_F(ExtensionsServiceTest, LoadAllExtensionsFromDirectorySuccess) {
   ValidateIntegerPref(good2, "state", Extension::ENABLED);
   ValidateIntegerPref(good2, "location", Extension::INTERNAL);
 
-  Extension* extension = loaded_[0];
+  const Extension* extension = loaded_[0];
   const UserScriptList& scripts = extension->content_scripts();
   ASSERT_EQ(2u, scripts.size());
   EXPECT_EQ(3u, scripts[0].url_patterns().size());
@@ -1276,7 +1276,7 @@ TEST_F(ExtensionsServiceTest, InstallAppsWithUnlimtedStorage) {
   PackAndInstallExtension(extensions_path.AppendASCII("app1"), true);
   ValidatePrefKeyCount(++pref_count);
   ASSERT_EQ(1u, service_->extensions()->size());
-  Extension* extension = service_->extensions()->at(0);
+  const Extension* extension = service_->extensions()->at(0);
   const std::string id1 = extension->id();
   EXPECT_TRUE(extension->HasApiPermission(
                   Extension::kUnlimitedStoragePermission));
@@ -1334,7 +1334,7 @@ TEST_F(ExtensionsServiceTest, InstallAppsAndCheckStorageProtection) {
   PackAndInstallExtension(extensions_path.AppendASCII("app1"), true);
   ValidatePrefKeyCount(++pref_count);
   ASSERT_EQ(1u, service_->extensions()->size());
-  Extension* extension = service_->extensions()->at(0);
+  const Extension* extension = service_->extensions()->at(0);
   EXPECT_TRUE(extension->is_app());
   const std::string id1 = extension->id();
   EXPECT_FALSE(service_->protected_storage_map_.empty());
@@ -1463,7 +1463,7 @@ TEST_F(ExtensionsServiceTest, UpdateExtension) {
   FilePath path = extensions_path.AppendASCII("good.crx");
 
   InstallExtension(path, true);
-  Extension* good = service_->extensions()->at(0);
+  const Extension* good = service_->extensions()->at(0);
   ASSERT_EQ("1.0.0.0", good->VersionString());
   ASSERT_EQ(good_crx, good->id());
 
@@ -1498,7 +1498,7 @@ TEST_F(ExtensionsServiceTest, UpdateWillNotDowngrade) {
   FilePath path = extensions_path.AppendASCII("good2.crx");
 
   InstallExtension(path, true);
-  Extension* good = service_->extensions()->at(0);
+  const Extension* good = service_->extensions()->at(0);
   ASSERT_EQ("1.0.0.1", good->VersionString());
   ASSERT_EQ(good_crx, good->id());
 
@@ -1518,7 +1518,7 @@ TEST_F(ExtensionsServiceTest, UpdateToSameVersionIsNoop) {
   FilePath path = extensions_path.AppendASCII("good.crx");
 
   InstallExtension(path, true);
-  Extension* good = service_->extensions()->at(0);
+  const Extension* good = service_->extensions()->at(0);
   ASSERT_EQ(good_crx, good->id());
   UpdateExtension(good_crx, path, FAILED_SILENTLY);
 }
@@ -1533,7 +1533,7 @@ TEST_F(ExtensionsServiceTest, UpdateExtensionPreservesState) {
   FilePath path = extensions_path.AppendASCII("good.crx");
 
   InstallExtension(path, true);
-  Extension* good = service_->extensions()->at(0);
+  const Extension* good = service_->extensions()->at(0);
   ASSERT_EQ("1.0.0.0", good->VersionString());
   ASSERT_EQ(good_crx, good->id());
 
@@ -1545,7 +1545,7 @@ TEST_F(ExtensionsServiceTest, UpdateExtensionPreservesState) {
   path = extensions_path.AppendASCII("good2.crx");
   UpdateExtension(good_crx, path, INSTALLED);
   ASSERT_EQ(1u, service_->disabled_extensions()->size());
-  Extension* good2 = service_->disabled_extensions()->at(0);
+  const Extension* good2 = service_->disabled_extensions()->at(0);
   ASSERT_EQ("1.0.0.1", good2->version()->GetString());
   EXPECT_TRUE(service_->IsIncognitoEnabled(good2));
 }
@@ -1603,7 +1603,7 @@ TEST_F(ExtensionsServiceTest, UpdatePendingExtension) {
 
   EXPECT_FALSE(ContainsKey(service_->pending_extensions(), kGoodId));
 
-  Extension* extension = service_->GetExtensionById(kGoodId, true);
+  const Extension* extension = service_->GetExtensionById(kGoodId, true);
   ASSERT_TRUE(extension);
 
   bool enabled = service_->GetExtensionById(kGoodId, false);
@@ -1630,7 +1630,7 @@ TEST_F(ExtensionsServiceTest, UpdatePendingTheme) {
 
   EXPECT_FALSE(ContainsKey(service_->pending_extensions(), theme_crx));
 
-  Extension* extension = service_->GetExtensionById(theme_crx, true);
+  const Extension* extension = service_->GetExtensionById(theme_crx, true);
   ASSERT_TRUE(extension);
 
   EXPECT_EQ(Extension::ENABLED,
@@ -1655,7 +1655,7 @@ TEST_F(ExtensionsServiceTest, UpdatePendingExternalCrx) {
 
   EXPECT_FALSE(ContainsKey(service_->pending_extensions(), theme_crx));
 
-  Extension* extension = service_->GetExtensionById(theme_crx, true);
+  const Extension* extension = service_->GetExtensionById(theme_crx, true);
   ASSERT_TRUE(extension);
 
   EXPECT_EQ(Extension::ENABLED,
@@ -1682,7 +1682,7 @@ TEST_F(ExtensionsServiceTest, UpdatePendingCrxThemeMismatch) {
 
   EXPECT_FALSE(ContainsKey(service_->pending_extensions(), theme_crx));
 
-  Extension* extension = service_->GetExtensionById(theme_crx, true);
+  const Extension* extension = service_->GetExtensionById(theme_crx, true);
   ASSERT_FALSE(extension);
 }
 
@@ -1739,7 +1739,7 @@ TEST_F(ExtensionsServiceTest, UpdatePendingExtensionAlreadyInstalled) {
   FilePath path = extensions_path.AppendASCII("good.crx");
   InstallExtension(path, true);
   ASSERT_EQ(1u, service_->extensions()->size());
-  Extension* good = service_->extensions()->at(0);
+  const Extension* good = service_->extensions()->at(0);
 
   EXPECT_FALSE(good->is_theme());
 
@@ -1794,7 +1794,7 @@ TEST_F(ExtensionsServiceTest, UnloadBlacklistedExtension) {
   FilePath path = extensions_path.AppendASCII("good.crx");
 
   InstallExtension(path, true);
-  Extension* good = service_->extensions()->at(0);
+  const Extension* good = service_->extensions()->at(0);
   EXPECT_EQ(good_crx, good->id());
   UpdateExtension(good_crx, path, FAILED_SILENTLY);
 
@@ -2127,7 +2127,7 @@ TEST_F(ExtensionsServiceTest, ClearExtensionData) {
   path = path.AppendASCII("extensions");
   path = path.AppendASCII("good.crx");
   InstallExtension(path, true);
-  Extension* extension = service_->GetExtensionById(good_crx, false);
+  const Extension* extension = service_->GetExtensionById(good_crx, false);
   ASSERT_TRUE(extension);
   GURL ext_url(extension->url());
   string16 origin_id =
diff --git a/chrome/browser/extensions/extensions_ui.cc b/chrome/browser/extensions/extensions_ui.cc
index 45b1cb6..d3f6a6c 100644
--- a/chrome/browser/extensions/extensions_ui.cc
+++ b/chrome/browser/extensions/extensions_ui.cc
@@ -58,8 +58,7 @@
 
 namespace {
 
-bool ShouldShowExtension(Extension* extension) {
-
+bool ShouldShowExtension(const Extension* extension) {
   // Don't show themes since this page's UI isn't really useful for themes.
   if (extension->is_theme())
     return false;
@@ -407,7 +406,7 @@ void ExtensionsDOMHandler::OnIconsLoaded(DictionaryValue* json) {
 }
 
 ExtensionResource ExtensionsDOMHandler::PickExtensionIcon(
-    Extension* extension) {
+    const Extension* extension) {
   return extension->GetIconResource(Extension::EXTENSION_ICON_MEDIUM,
                                     ExtensionIconSet::MATCH_BIGGER);
 }
@@ -459,7 +458,7 @@ void ExtensionsDOMHandler::HandleEnableMessage(const ListValue* args) {
   if (enable_str == "true") {
     ExtensionPrefs* prefs = extensions_service_->extension_prefs();
     if (prefs->DidExtensionEscalatePermissions(extension_id)) {
-      Extension* extension =
+      const Extension* extension =
           extensions_service_->GetExtensionById(extension_id, true);
       ShowExtensionDisabledDialog(extensions_service_,
                                   dom_ui_->GetProfile(), extension);
@@ -476,8 +475,8 @@ void ExtensionsDOMHandler::HandleEnableIncognitoMessage(const ListValue* args) {
   std::string extension_id, enable_str;
   CHECK(args->GetString(0, &extension_id));
   CHECK(args->GetString(1, &enable_str));
-  Extension* extension = extensions_service_->GetExtensionById(extension_id,
-                                                               true);
+  const Extension* extension =
+      extensions_service_->GetExtensionById(extension_id, true);
   DCHECK(extension);
 
   // Flipping the incognito bit will generate unload/load notifications for the
@@ -501,15 +500,15 @@ void ExtensionsDOMHandler::HandleAllowFileAccessMessage(const ListValue* args) {
   std::string extension_id, allow_str;
   CHECK(args->GetString(0, &extension_id));
   CHECK(args->GetString(1, &allow_str));
-  Extension* extension = extensions_service_->GetExtensionById(extension_id,
-                                                               true);
+  const Extension* extension =
+      extensions_service_->GetExtensionById(extension_id, true);
   DCHECK(extension);
 
   extensions_service_->SetAllowFileAccess(extension, allow_str == "true");
 }
 
 void ExtensionsDOMHandler::HandleUninstallMessage(const ListValue* args) {
-  Extension* extension = GetExtension(args);
+  const Extension* extension = GetExtension(args);
   if (!extension)
     return;
 
@@ -527,7 +526,7 @@ void ExtensionsDOMHandler::InstallUIProceed() {
 
   // The extension can be uninstalled in another window while the UI was
   // showing. Do nothing in that case.
-  Extension* extension =
+  const Extension* extension =
       extensions_service_->GetExtensionById(extension_id_prompting_, true);
   if (!extension)
     return;
@@ -542,7 +541,7 @@ void ExtensionsDOMHandler::InstallUIAbort() {
 }
 
 void ExtensionsDOMHandler::HandleOptionsMessage(const ListValue* args) {
-  Extension* extension = GetExtension(args);
+  const Extension* extension = GetExtension(args);
   if (!extension || extension->options_url().is_empty())
     return;
   dom_ui_->GetProfile()->GetExtensionProcessManager()->OpenOptionsPage(
@@ -703,7 +702,7 @@ void ExtensionsDOMHandler::Observe(NotificationType type,
   }
 }
 
-Extension* ExtensionsDOMHandler::GetExtension(const ListValue* args) {
+const Extension* ExtensionsDOMHandler::GetExtension(const ListValue* args) {
   std::string extension_id = WideToASCII(ExtractStringValue(args));
   CHECK(!extension_id.empty());
   return extensions_service_->GetExtensionById(extension_id, true);
@@ -846,7 +845,7 @@ DictionaryValue* ExtensionsDOMHandler::CreateExtensionDetailValue(
 }
 
 std::vector<ExtensionPage> ExtensionsDOMHandler::GetActivePagesForExtension(
-    Extension* extension) {
+    const Extension* extension) {
   std::vector<ExtensionPage> result;
 
   // Get the extension process's active views.
@@ -872,7 +871,7 @@ std::vector<ExtensionPage> ExtensionsDOMHandler::GetActivePagesForExtension(
 
 void ExtensionsDOMHandler::GetActivePagesForExtensionProcess(
     RenderProcessHost* process,
-    Extension* extension,
+    const Extension* extension,
     std::vector<ExtensionPage> *result) {
   if (!process)
     return;
diff --git a/chrome/browser/extensions/extensions_ui.h b/chrome/browser/extensions/extensions_ui.h
index 5660eaa..c8c6143 100644
--- a/chrome/browser/extensions/extensions_ui.h
+++ b/chrome/browser/extensions/extensions_ui.h
@@ -178,7 +178,7 @@ class ExtensionsDOMHandler
   void HandleSelectFilePathMessage(const ListValue* args);
 
   // Utility for callbacks that get an extension ID as the sole argument.
-  Extension* GetExtension(const ListValue* args);
+  const Extension* GetExtension(const ListValue* args);
 
   // Forces a UI update if appropriate after a notification is received.
   void MaybeUpdateAfterNotification();
@@ -198,15 +198,16 @@ class ExtensionsDOMHandler
                        const NotificationDetails& details);
 
   // Helper that lists the current active html pages for an extension.
-  std::vector<ExtensionPage> GetActivePagesForExtension(Extension* extension);
+  std::vector<ExtensionPage> GetActivePagesForExtension(
+      const Extension* extension);
   void GetActivePagesForExtensionProcess(
       RenderProcessHost* process,
-      Extension* extension,
+      const Extension* extension,
       std::vector<ExtensionPage> *result);
 
   // Returns the best icon to display in the UI for an extension, or an empty
   // ExtensionResource if no good icon exists.
-  ExtensionResource PickExtensionIcon(Extension* extension);
+  ExtensionResource PickExtensionIcon(const Extension* extension);
 
   // Loads the extension resources into the json data, then calls OnIconsLoaded.
   // Takes ownership of |icons|.
diff --git a/chrome/browser/extensions/image_loading_tracker.cc b/chrome/browser/extensions/image_loading_tracker.cc
index f4f9bfd..496c3ad 100644
--- a/chrome/browser/extensions/image_loading_tracker.cc
+++ b/chrome/browser/extensions/image_loading_tracker.cc
@@ -134,7 +134,7 @@ ImageLoadingTracker::~ImageLoadingTracker() {
     loader_->StopTracking();
 }
 
-void ImageLoadingTracker::LoadImage(Extension* extension,
+void ImageLoadingTracker::LoadImage(const Extension* extension,
                                     const ExtensionResource& resource,
                                     const gfx::Size& max_size,
                                     CacheParam cache) {
@@ -187,7 +187,7 @@ void ImageLoadingTracker::Observe(NotificationType type,
   DCHECK(type == NotificationType::EXTENSION_UNLOADED ||
          type == NotificationType::EXTENSION_UNLOADED_DISABLED);
 
-  Extension* extension = Details<Extension>(details).ptr();
+  const Extension* extension = Details<const Extension>(details).ptr();
 
   // Remove all entries in the load_map_ referencing the extension. This ensures
   // we don't attempt to cache the image when the load completes.
diff --git a/chrome/browser/extensions/image_loading_tracker.h b/chrome/browser/extensions/image_loading_tracker.h
index bac2f04..0ce3703 100644
--- a/chrome/browser/extensions/image_loading_tracker.h
+++ b/chrome/browser/extensions/image_loading_tracker.h
@@ -64,13 +64,13 @@ class ImageLoadingTracker : public NotificationObserver {
   // |max_size| it will be resized to those dimensions. IMPORTANT NOTE: this
   // function may call back your observer synchronously (ie before it returns)
   // if the image was found in the cache.
-  void LoadImage(Extension* extension,
+  void LoadImage(const Extension* extension,
                  const ExtensionResource& resource,
                  const gfx::Size& max_size,
                  CacheParam cache);
 
  private:
-  typedef std::map<int, Extension*> LoadMap;
+  typedef std::map<int, const Extension*> LoadMap;
 
   class ImageLoader;
 
diff --git a/chrome/browser/extensions/image_loading_tracker_unittest.cc b/chrome/browser/extensions/image_loading_tracker_unittest.cc
index d23e2f6..57b5268 100644
--- a/chrome/browser/extensions/image_loading_tracker_unittest.cc
+++ b/chrome/browser/extensions/image_loading_tracker_unittest.cc
@@ -163,7 +163,7 @@ TEST_F(ImageLoadingTrackerTest, DeleteExtensionWhileWaitingForCache) {
   NotificationService::current()->Notify(
       NotificationType::EXTENSION_UNLOADED,
       NotificationService::AllSources(),
-      Details<Extension>(extension.get()));
+      Details<const Extension>(extension.get()));
 
   // Chuck the extension, that way if anyone tries to access it we should crash
   // or get valgrind errors.
diff --git a/chrome/browser/extensions/page_action_apitest.cc b/chrome/browser/extensions/page_action_apitest.cc
index c03c030..95e029e 100644
--- a/chrome/browser/extensions/page_action_apitest.cc
+++ b/chrome/browser/extensions/page_action_apitest.cc
@@ -18,7 +18,7 @@
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PageAction) {
   ASSERT_TRUE(test_server()->Start());
   ASSERT_TRUE(RunExtensionTest("page_action/basics")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
   {
     // Tell the extension to update the page action state.
@@ -62,7 +62,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PageAction) {
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PageActionAddPopup) {
   // Load the extension, which has no default popup.
   ASSERT_TRUE(RunExtensionTest("page_action/add_popup")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   int tab_id = ExtensionTabUtil::GetTabId(browser()->GetSelectedTabContents());
@@ -107,7 +107,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PageActionAddPopup) {
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PageActionRemovePopup) {
   // Load the extension, which has a page action with a default popup.
   ASSERT_TRUE(RunExtensionTest("page_action/remove_popup")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   int tab_id = ExtensionTabUtil::GetTabId(browser()->GetSelectedTabContents());
@@ -136,7 +136,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PageActionRemovePopup) {
 // break.
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, OldPageActions) {
   ASSERT_TRUE(RunExtensionTest("page_action/old_api")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   // Have the extension enable the page action.
@@ -161,7 +161,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, OldPageActions) {
 // Tests popups in page actions.
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, ShowPageActionPopup) {
   ASSERT_TRUE(RunExtensionTest("page_action/popup")) << message_;
-  Extension* extension = GetSingleLoadedExtension();
+  const Extension* extension = GetSingleLoadedExtension();
   ASSERT_TRUE(extension) << message_;
 
   ASSERT_TRUE(WaitForPageActionVisibilityChangeTo(1));
diff --git a/chrome/browser/extensions/sandboxed_extension_unpacker.h b/chrome/browser/extensions/sandboxed_extension_unpacker.h
index 383156b..8438482 100644
--- a/chrome/browser/extensions/sandboxed_extension_unpacker.h
+++ b/chrome/browser/extensions/sandboxed_extension_unpacker.h
@@ -29,7 +29,7 @@ class SandboxedExtensionUnpackerClient
   // for deleting this memory.
   virtual void OnUnpackSuccess(const FilePath& temp_dir,
                                const FilePath& extension_root,
-                               Extension* extension) = 0;
+                               const Extension* extension) = 0;
   virtual void OnUnpackFailure(const std::string& error) = 0;
 
  protected:
diff --git a/chrome/browser/extensions/sandboxed_extension_unpacker_unittest.cc b/chrome/browser/extensions/sandboxed_extension_unpacker_unittest.cc
index 0ba87d5..4d893e1 100644
--- a/chrome/browser/extensions/sandboxed_extension_unpacker_unittest.cc
+++ b/chrome/browser/extensions/sandboxed_extension_unpacker_unittest.cc
@@ -25,7 +25,7 @@ using testing::Invoke;
 
 void OnUnpackSuccess(const FilePath& temp_dir,
                      const FilePath& extension_root,
-                     Extension* extension) {
+                     const Extension* extension) {
   // Don't delete temp_dir here, we need to do some post op checking.
 }
 
@@ -37,7 +37,7 @@ class MockSandboxedExtensionUnpackerClient
   MOCK_METHOD3(OnUnpackSuccess,
                void(const FilePath& temp_dir,
                     const FilePath& extension_root,
-                    Extension* extension));
+                    const Extension* extension));
 
   MOCK_METHOD1(OnUnpackFailure,
                void(const std::string& error));
diff --git a/chrome/browser/extensions/theme_installed_infobar_delegate.cc b/chrome/browser/extensions/theme_installed_infobar_delegate.cc
index 6d00c22..ebfbe98 100644
--- a/chrome/browser/extensions/theme_installed_infobar_delegate.cc
+++ b/chrome/browser/extensions/theme_installed_infobar_delegate.cc
@@ -81,7 +81,7 @@ bool ThemeInstalledInfoBarDelegate::Cancel() {
   if (!previous_theme_id_.empty()) {
     ExtensionsService* service = profile_->GetExtensionsService();
     if (service) {
-      Extension* previous_theme =
+      const Extension* previous_theme =
           service->GetExtensionById(previous_theme_id_, true);
       if (previous_theme) {
         profile_->SetTheme(previous_theme);
@@ -102,7 +102,7 @@ void ThemeInstalledInfoBarDelegate::Observe(
     case NotificationType::BROWSER_THEME_CHANGED: {
       // If the new theme is different from what this info bar is associated
       // with, close this info bar since it is no longer relevant.
-      Extension* extension = Details<Extension>(details).ptr();
+      const Extension* extension = Details<const Extension>(details).ptr();
       if (!extension || theme_id_ != extension->id())
         tab_contents_->RemoveInfoBar(this);
       break;
@@ -113,6 +113,6 @@ void ThemeInstalledInfoBarDelegate::Observe(
   }
 }
 
-bool ThemeInstalledInfoBarDelegate::MatchesTheme(Extension* theme) {
+bool ThemeInstalledInfoBarDelegate::MatchesTheme(const Extension* theme) {
   return (theme && theme->id() == theme_id_);
 }
diff --git a/chrome/browser/extensions/theme_installed_infobar_delegate.h b/chrome/browser/extensions/theme_installed_infobar_delegate.h
index 2c54fa5..b1ed99e 100644
--- a/chrome/browser/extensions/theme_installed_infobar_delegate.h
+++ b/chrome/browser/extensions/theme_installed_infobar_delegate.h
@@ -33,7 +33,7 @@ class ThemeInstalledInfoBarDelegate : public ConfirmInfoBarDelegate,
 
   // Returns true if the given theme is the same as the one associated with this
   // info bar.
-  bool MatchesTheme(Extension* theme);
+  bool MatchesTheme(const Extension* theme);
 
   // NotificationObserver implementation.
   virtual void Observe(NotificationType type,
diff --git a/chrome/browser/extensions/user_script_listener.cc b/chrome/browser/extensions/user_script_listener.cc
index 4e84045..c553b1f 100644
--- a/chrome/browser/extensions/user_script_listener.cc
+++ b/chrome/browser/extensions/user_script_listener.cc
@@ -98,7 +98,7 @@ void UserScriptListener::ReplaceURLPatterns(const URLPatterns& patterns) {
   url_patterns_ = patterns;
 }
 
-void UserScriptListener::CollectURLPatterns(Extension* extension,
+void UserScriptListener::CollectURLPatterns(const Extension* extension,
                                             URLPatterns* patterns) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
@@ -118,12 +118,13 @@ void UserScriptListener::Observe(NotificationType type,
 
   switch (type.value) {
     case NotificationType::EXTENSION_LOADED: {
-      Extension* extension = Details<Extension>(details).ptr();
+      const Extension* extension = Details<const Extension>(details).ptr();
       if (extension->content_scripts().empty())
         return;  // no new patterns from this extension.
 
       URLPatterns new_patterns;
-      CollectURLPatterns(Details<Extension>(details).ptr(), &new_patterns);
+      CollectURLPatterns(Details<const Extension>(details).ptr(),
+                         &new_patterns);
       if (!new_patterns.empty()) {
         BrowserThread::PostTask(
             BrowserThread::IO, FROM_HERE,
@@ -134,7 +135,8 @@ void UserScriptListener::Observe(NotificationType type,
     }
 
     case NotificationType::EXTENSION_UNLOADED: {
-      Extension* unloaded_extension = Details<Extension>(details).ptr();
+      const Extension* unloaded_extension =
+          Details<const Extension>(details).ptr();
       if (unloaded_extension->content_scripts().empty())
         return;  // no patterns to delete for this extension.
 
diff --git a/chrome/browser/extensions/user_script_listener.h b/chrome/browser/extensions/user_script_listener.h
index 05de21a..3ac83ed 100644
--- a/chrome/browser/extensions/user_script_listener.h
+++ b/chrome/browser/extensions/user_script_listener.h
@@ -82,7 +82,7 @@ class UserScriptListener
 
   // Helper to collect the extension's user script URL patterns in a list and
   // return it.
-  void CollectURLPatterns(Extension* extension, URLPatterns* patterns);
+  void CollectURLPatterns(const Extension* extension, URLPatterns* patterns);
 
   // NotificationObserver
   virtual void Observe(NotificationType type,
diff --git a/chrome/browser/extensions/user_script_master.cc b/chrome/browser/extensions/user_script_master.cc
index 55c6df2..1712bb6 100644
--- a/chrome/browser/extensions/user_script_master.cc
+++ b/chrome/browser/extensions/user_script_master.cc
@@ -339,7 +339,7 @@ void UserScriptMaster::Observe(NotificationType type,
       break;
     case NotificationType::EXTENSION_LOADED: {
       // Add any content scripts inside the extension.
-      Extension* extension = Details<Extension>(details).ptr();
+      const Extension* extension = Details<const Extension>(details).ptr();
       bool incognito_enabled = profile_->GetExtensionsService()->
           IsIncognitoEnabled(extension);
       bool allow_file_access = profile_->GetExtensionsService()->
@@ -357,7 +357,7 @@ void UserScriptMaster::Observe(NotificationType type,
     }
     case NotificationType::EXTENSION_UNLOADED: {
       // Remove any content scripts.
-      Extension* extension = Details<Extension>(details).ptr();
+      const Extension* extension = Details<const Extension>(details).ptr();
       UserScriptList new_lone_scripts;
       for (UserScriptList::iterator iter = lone_scripts_.begin();
            iter != lone_scripts_.end(); ++iter) {
@@ -373,7 +373,7 @@ void UserScriptMaster::Observe(NotificationType type,
       break;
     }
     case NotificationType::EXTENSION_USER_SCRIPTS_UPDATED: {
-      Extension* extension = Details<Extension>(details).ptr();
+      const Extension* extension = Details<const Extension>(details).ptr();
       UserScriptList new_lone_scripts;
       bool incognito_enabled = profile_->GetExtensionsService()->
           IsIncognitoEnabled(extension);