Disable an extension when it is upgraded to a version that requires more

permissions then before, and prompt the user to re-enable.

Incidentally, this required adding support for disabling extensions.

BUG=12140
TEST=covered by unit tests

Review URL: http://codereview.chromium.org/165414

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@23480 0039d316-1c4b-4281-b951-d872f2087c98

25 files changed, 460 insertions, 74 deletions

diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 3974b03..e2026c3 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -2063,8 +2063,16 @@ each locale. -->
       <message name="IDS_THEME_INSTALL_INFOBAR_UNDO_BUTTON" desc="Text displayed on the button to undo a theme installation and go back to the previous theme.">
         Undo
       </message>
-      
-      <!-- Extesion install prompt -->
+
+      <!-- Extension disabled info bar -->
+      <message name="IDS_EXTENSION_DISABLED_INFOBAR_LABEL" desc="Text displayed on an infobar when an extension was disabled due to a new upgrade requiring an explicit permission check from the user.">
+        The newest version of the extension "<ph name="EXTENSION_NAME">$1<ex>Flashblock</ex></ph>" requires more permissions, so it has been disabled.
+      </message>
+      <message name="IDS_EXTENSION_DISABLED_INFOBAR_ENABLE_BUTTON" desc="Text displayed on the button to re-enable the disabled extension.">
+        Reenable
+      </message>
+
+      <!-- Extension install prompt -->
       <message name="IDS_EXTENSION_PROMPT_TITLE" desc="Titlebar of the extension installation prompt window">
         Confirm Installation
       </message>
diff --git a/chrome/browser/browser.cc b/chrome/browser/browser.cc
index 8183090..5478464 100644
--- a/chrome/browser/browser.cc
+++ b/chrome/browser/browser.cc
@@ -23,6 +23,7 @@
 #include "chrome/browser/download/download_manager.h"
 #include "chrome/browser/download/download_shelf.h"
 #include "chrome/browser/download/download_started_animation.h"
+#include "chrome/browser/extensions/extension_disabled_infobar_delegate.h"
 #include "chrome/browser/find_bar.h"
 #include "chrome/browser/find_bar_controller.h"
 #include "chrome/browser/location_bar.h"
@@ -188,6 +189,8 @@ Browser::Browser(Type type, Profile* profile)
 
   registrar_.Add(this, NotificationType::SSL_VISIBLE_STATE_CHANGED,
                  NotificationService::AllSources());
+  registrar_.Add(this, NotificationType::EXTENSION_UPDATE_DISABLED,
+                 NotificationService::AllSources());
   registrar_.Add(this, NotificationType::EXTENSION_UNLOADED,
                  NotificationService::AllSources());
   registrar_.Add(this, NotificationType::BROWSER_THEME_CHANGED,
@@ -2079,6 +2082,14 @@ void Browser::Observe(NotificationType type,
         UpdateToolbar(false);
       break;
 
+    case NotificationType::EXTENSION_UPDATE_DISABLED: {
+      // Show the UI.
+      ExtensionsService* service = Source<ExtensionsService>(source).ptr();
+      Extension* extension = Details<Extension>(details).ptr();
+      ShowExtensionDisabledUI(service, profile_, extension);
+      break;
+    }
+
     case NotificationType::EXTENSION_UNLOADED: {
       // Close any tabs from the unloaded extension.
       Extension* extension = Details<Extension>(details).ptr();
diff --git a/chrome/browser/browser_resources.grd b/chrome/browser/browser_resources.grd
index 1165f13..385d5d7 100644
--- a/chrome/browser/browser_resources.grd
+++ b/chrome/browser/browser_resources.grd
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This comment is only here because changes to resources are not picked up
-without changes to the corresponding grd file. aa1 -->
+without changes to the corresponding grd file. mp6 -->
 <grit latest_public_release="0" current_release="1">
   <outputs>
     <output filename="grit/browser_resources.h" type="rc_header">
diff --git a/chrome/browser/extensions/extension_browsertest.cc b/chrome/browser/extensions/extension_browsertest.cc
index 7ef3239..04d496a 100644
--- a/chrome/browser/extensions/extension_browsertest.cc
+++ b/chrome/browser/extensions/extension_browsertest.cc
@@ -42,14 +42,15 @@ void ExtensionBrowserTest::SetUpCommandLine(CommandLine* command_line) {
 bool ExtensionBrowserTest::LoadExtension(const FilePath& path) {
   ExtensionsService* service = browser()->profile()->GetExtensionsService();
   size_t num_before = service->extensions()->size();
-  registrar_.Add(this, NotificationType::EXTENSIONS_LOADED,
-                 NotificationService::AllSources());
-  service->LoadExtension(path);
-  MessageLoop::current()->PostDelayedTask(FROM_HERE, new MessageLoop::QuitTask,
-      kTimeoutMs);
-  ui_test_utils::RunMessageLoop();
-  registrar_.Remove(this, NotificationType::EXTENSIONS_LOADED,
-                    NotificationService::AllSources());
+  {
+    NotificationRegistrar registrar;
+    registrar.Add(this, NotificationType::EXTENSIONS_LOADED,
+                  NotificationService::AllSources());
+    service->LoadExtension(path);
+    MessageLoop::current()->PostDelayedTask(
+        FROM_HERE, new MessageLoop::QuitTask, kTimeoutMs);
+    ui_test_utils::RunMessageLoop();
+  }
   size_t num_after = service->extensions()->size();
   if (num_after != (num_before + 1))
     return false;
@@ -57,21 +58,26 @@ bool ExtensionBrowserTest::LoadExtension(const FilePath& path) {
   return WaitForExtensionHostsToLoad();
 }
 
-bool ExtensionBrowserTest::InstallExtension(const FilePath& path) {
+bool ExtensionBrowserTest::InstallExtension(const FilePath& path,
+                                            int expected_change) {
   ExtensionsService* service = browser()->profile()->GetExtensionsService();
   service->set_show_extensions_prompts(false);
   size_t num_before = service->extensions()->size();
 
-  registrar_.Add(this, NotificationType::EXTENSIONS_LOADED,
-                 NotificationService::AllSources());
-  service->InstallExtension(path);
-  MessageLoop::current()->PostDelayedTask(FROM_HERE, new MessageLoop::QuitTask,
-      kTimeoutMs);
-  ui_test_utils::RunMessageLoop();
-  registrar_.Remove(this, NotificationType::EXTENSIONS_LOADED,
-                    NotificationService::AllSources());
+  {
+    NotificationRegistrar registrar;
+    registrar.Add(this, NotificationType::EXTENSIONS_LOADED,
+                  NotificationService::AllSources());
+    registrar.Add(this, NotificationType::EXTENSION_UPDATE_DISABLED,
+                  NotificationService::AllSources());
+    service->InstallExtension(path);
+    MessageLoop::current()->PostDelayedTask(
+        FROM_HERE, new MessageLoop::QuitTask, kTimeoutMs);
+    ui_test_utils::RunMessageLoop();
+  }
+
   size_t num_after = service->extensions()->size();
-  if (num_after != (num_before + 1)) {
+  if (num_after != (num_before + expected_change)) {
     std::cout << "Num extensions before: " << IntToString(num_before) << " "
               << "num after: " << IntToString(num_after) << " "
               << "Installed extensions follow:\n";
@@ -147,14 +153,19 @@ bool ExtensionBrowserTest::WaitForExtensionHostsToLoad() {
 }
 
 void ExtensionBrowserTest::Observe(NotificationType type,
-                     const NotificationSource& source,
-                     const NotificationDetails& details) {
+                                   const NotificationSource& source,
+                                   const NotificationDetails& details) {
   switch (type.value) {
     case NotificationType::EXTENSIONS_LOADED:
       std::cout << "Got EXTENSION_LOADED notification.\n";
       MessageLoopForUI::current()->Quit();
       break;
 
+    case NotificationType::EXTENSION_UPDATE_DISABLED:
+      std::cout << "Got EXTENSIONS_DISABLED_LOAD notification.\n";
+      MessageLoopForUI::current()->Quit();
+      break;
+
     default:
       NOTREACHED();
       break;
diff --git a/chrome/browser/extensions/extension_browsertest.h b/chrome/browser/extensions/extension_browsertest.h
index 5990f5c..72b0de4 100644
--- a/chrome/browser/extensions/extension_browsertest.h
+++ b/chrome/browser/extensions/extension_browsertest.h
@@ -22,7 +22,11 @@ class ExtensionBrowserTest
  protected:
   virtual void SetUpCommandLine(CommandLine* command_line);
   bool LoadExtension(const FilePath& path);
-  bool InstallExtension(const FilePath& path);
+  // |expected_change| indicates how many extensions should be installed (or
+  // disabled, if negative).
+  // 1 means you expect a new install, 0 means you expect an upgrade, -1 means
+  // you expect a failed upgrade.
+  bool InstallExtension(const FilePath& path, int expected_change);
   void UninstallExtension(const std::string& extension_id);
 
   // Wait for the number of visible page actions to change to |count|.
@@ -37,8 +41,6 @@ class ExtensionBrowserTest
                        const NotificationSource& source,
                        const NotificationDetails& details);
   bool WaitForExtensionHostsToLoad();
-
-  NotificationRegistrar registrar_;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_BROWSER_TEST_H_
diff --git a/chrome/browser/extensions/extension_browsertests_misc.cc b/chrome/browser/extensions/extension_browsertests_misc.cc
index ae3ece7..a630f52 100644
--- a/chrome/browser/extensions/extension_browsertests_misc.cc
+++ b/chrome/browser/extensions/extension_browsertests_misc.cc
@@ -151,7 +151,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, Incognito) {
   Browser::OpenURLOffTheRecord(browser()->profile(),
                                GURL(chrome::kChromeUIExtensionsURL));
 
-  ASSERT_TRUE(InstallExtension(test_data_dir_.AppendASCII("good.crx")));
+  ASSERT_TRUE(InstallExtension(test_data_dir_.AppendASCII("good.crx"), 1));
   UninstallExtension("ldnnhddmnhbkjipkidpdiheffobcpfmf");
 }
 
@@ -415,3 +415,49 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, MessagingContentScript) {
       host->render_view_host(), L"", L"testDisconnectOnClose()", &result);
   EXPECT_TRUE(result);
 }
+
+// Tests the process of updating an extension to one that requires higher
+// permissions.
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, UpdatePermissions) {
+  TabContents* contents = browser()->GetSelectedTabContents();
+  ASSERT_TRUE(contents);
+
+  // Install the initial version, which should happen just fine.
+  ASSERT_TRUE(InstallExtension(
+      test_data_dir_.AppendASCII("permissions-low-v1.crx"), 1));
+  DCHECK_EQ(0, contents->infobar_delegate_count());
+
+  // Upgrade to a version that wants more permissions. We should disable the
+  // extension and prompt the user to reenable.
+  ASSERT_TRUE(InstallExtension(
+      test_data_dir_.AppendASCII("permissions-high-v2.crx"), -1));
+  EXPECT_EQ(1, contents->infobar_delegate_count());
+
+  ExtensionsService* service = browser()->profile()->GetExtensionsService();
+  EXPECT_EQ(0u, service->extensions()->size());
+  ASSERT_EQ(1u, service->disabled_extensions()->size());
+
+  // Now try reenabling it, which should also dismiss the infobar.
+  service->EnableExtension(service->disabled_extensions()->at(0)->id());
+  EXPECT_EQ(0, contents->infobar_delegate_count());
+  EXPECT_EQ(1u, service->extensions()->size());
+  EXPECT_EQ(0u, service->disabled_extensions()->size());
+}
+
+// Tests that we can uninstall a disabled extension.
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, UninstallDisabled) {
+  // Install and upgrade, so that we have a disabled extension.
+  ASSERT_TRUE(InstallExtension(
+      test_data_dir_.AppendASCII("permissions-low-v1.crx"), 1));
+  ASSERT_TRUE(InstallExtension(
+      test_data_dir_.AppendASCII("permissions-high-v2.crx"), -1));
+
+  ExtensionsService* service = browser()->profile()->GetExtensionsService();
+  EXPECT_EQ(0u, service->extensions()->size());
+  ASSERT_EQ(1u, service->disabled_extensions()->size());
+
+  // Now try uninstalling it.
+  UninstallExtension(service->disabled_extensions()->at(0)->id());
+  EXPECT_EQ(0u, service->extensions()->size());
+  EXPECT_EQ(0u, service->disabled_extensions()->size());
+}
diff --git a/chrome/browser/extensions/extension_disabled_infobar_delegate.cc b/chrome/browser/extensions/extension_disabled_infobar_delegate.cc
new file mode 100644
index 0000000..f812392
--- /dev/null
+++ b/chrome/browser/extensions/extension_disabled_infobar_delegate.cc
@@ -0,0 +1,92 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/extensions/extension_disabled_infobar_delegate.h"
+
+#include "app/l10n_util.h"
+#include "chrome/browser/extensions/extensions_service.h"
+#include "chrome/browser/tab_contents/infobar_delegate.h"
+#include "chrome/browser/tab_contents/tab_contents.h"
+#include "chrome/browser/browser_list.h"
+#include "chrome/common/notification_registrar.h"
+#include "chrome/common/notification_service.h"
+#include "grit/generated_resources.h"
+
+class ExtensionDisabledInfobarDelegate
+    : public ConfirmInfoBarDelegate,
+      public NotificationObserver {
+ public:
+  ExtensionDisabledInfobarDelegate(TabContents* tab_contents,
+                                   ExtensionsService* service,
+                                   const std::string& extension_id,
+                                   const std::string& extension_name)
+      : ConfirmInfoBarDelegate(tab_contents),
+        tab_contents_(tab_contents),
+        service_(service),
+        extension_id_(extension_id),
+        extension_name_(extension_name) {
+    // The user might re-enable the extension in other ways, so watch for that.
+    registrar_.Add(this, NotificationType::EXTENSIONS_LOADED,
+                   Source<ExtensionsService>(service));
+  }
+  virtual void InfoBarClosed() {
+    delete this;
+  }
+  virtual std::wstring GetMessageText() const {
+    return l10n_util::GetStringF(IDS_EXTENSION_DISABLED_INFOBAR_LABEL,
+                                 UTF8ToWide(extension_name_));
+  }
+  virtual SkBitmap* GetIcon() const {
+    return NULL;
+  }
+  virtual int GetButtons() const {
+    return BUTTON_OK;
+  }
+  virtual std::wstring GetButtonLabel(
+      ConfirmInfoBarDelegate::InfoBarButton button) const {
+    return l10n_util::GetString(IDS_EXTENSION_DISABLED_INFOBAR_ENABLE_BUTTON);
+  }
+  virtual bool Accept() {
+    service_->EnableExtension(extension_id_);
+    return true;
+  }
+
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details) {
+    DCHECK(type == NotificationType::EXTENSIONS_LOADED);
+    ExtensionList* extensions = Details<ExtensionList>(details).ptr();
+
+    for (ExtensionList::iterator iter = extensions->begin();
+         iter != extensions->end(); ++iter) {
+       if ((*iter)->id() == extension_id_) {
+         // TODO(mpcomplete): This doesn't seem to always result in us getting
+         // deleted.
+         tab_contents_->RemoveInfoBar(this);
+         return;
+       }
+    }
+  }
+
+ private:
+  NotificationRegistrar registrar_;
+  TabContents* tab_contents_;
+  ExtensionsService* service_;
+  std::string extension_id_;
+  std::string extension_name_;
+};
+
+void ShowExtensionDisabledUI(ExtensionsService* service, Profile* profile,
+                             Extension* extension) {
+  Browser* browser = BrowserList::GetLastActiveWithProfile(profile);
+  if (!browser)
+    return;
+
+  TabContents* tab_contents = browser->GetSelectedTabContents();
+  if (!tab_contents)
+    return;
+
+  tab_contents->AddInfoBar(new ExtensionDisabledInfobarDelegate(
+      tab_contents, service, extension->id(), extension->name()));
+}
diff --git a/chrome/browser/extensions/extension_disabled_infobar_delegate.h b/chrome/browser/extensions/extension_disabled_infobar_delegate.h
new file mode 100644
index 0000000..0c66ce9
--- /dev/null
+++ b/chrome/browser/extensions/extension_disabled_infobar_delegate.h
@@ -0,0 +1,19 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_DISABLED_INFOBAR_DELEGATE_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_DISABLED_INFOBAR_DELEGATE_H_
+
+#include <string>
+
+class Extension;
+class ExtensionsService;
+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);
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_DISABLED_INFOBAR_DELEGATE_H_
diff --git a/chrome/browser/extensions/extension_prefs.cc b/chrome/browser/extensions/extension_prefs.cc
index bc88831..84ee99d 100644
--- a/chrome/browser/extensions/extension_prefs.cc
+++ b/chrome/browser/extensions/extension_prefs.cc
@@ -299,7 +299,7 @@ void ExtensionPrefs::SetShelfToolstripOrder(const URLList& urls) {
 }
 
 void ExtensionPrefs::OnExtensionInstalled(Extension* extension) {
-  std::string id = extension->id();
+  const std::string& id = extension->id();
   UpdateExtensionPref(id, kPrefState,
                       Value::CreateIntegerValue(Extension::ENABLED));
   UpdateExtensionPref(id, kPrefLocation,
@@ -326,12 +326,37 @@ void ExtensionPrefs::OnExtensionUninstalled(const Extension* extension,
   }
 }
 
+Extension::State ExtensionPrefs::GetExtensionState(
+    const std::string& extension_id) {
+  DictionaryValue* extension = GetExtensionPref(extension_id);
+
+  // If the extension doesn't have a pref, it's a --load-extension.
+  if (!extension)
+    return Extension::ENABLED;
+
+  int state = -1;
+  if (!extension->GetInteger(kPrefState, &state) ||
+      state < 0 || state >= Extension::NUM_STATES) {
+    LOG(ERROR) << "Bad or missing pref 'state' for extension '"
+               << extension_id << "'";
+    return Extension::ENABLED;
+  }
+  return static_cast<Extension::State>(state);
+}
+
+void ExtensionPrefs::SetExtensionState(Extension* extension,
+                                       Extension::State state) {
+  UpdateExtensionPref(extension->id(), kPrefState,
+                      Value::CreateIntegerValue(state));
+  prefs_->SavePersistentPrefs();
+}
+
 bool ExtensionPrefs::UpdateExtensionPref(const std::string& extension_id,
                                          const std::wstring& key,
                                          Value* data_value) {
   DictionaryValue* extension = GetOrCreateExtensionPref(extension_id);
   if (!extension->Set(key, data_value)) {
-    NOTREACHED() << L"Cannot modify key: '" << key.c_str()
+    NOTREACHED() << "Cannot modify key: '" << key.c_str()
                  << "' for extension: '" << extension_id.c_str() << "'";
     return false;
   }
@@ -359,3 +384,12 @@ DictionaryValue* ExtensionPrefs::GetOrCreateExtensionPref(
   }
   return extension;
 }
+
+DictionaryValue* ExtensionPrefs::GetExtensionPref(
+    const std::string& extension_id) {
+  const DictionaryValue* dict = prefs_->GetDictionary(kExtensionsPref);
+  DictionaryValue* extension = NULL;
+  std::wstring id = ASCIIToWide(extension_id);
+  dict->GetDictionary(id, &extension);
+  return extension;
+}
diff --git a/chrome/browser/extensions/extension_prefs.h b/chrome/browser/extensions/extension_prefs.h
index c819bcd..291556c 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -43,6 +43,12 @@ class ExtensionPrefs {
   void OnExtensionUninstalled(const Extension* extension,
                               bool external_uninstall);
 
+  // Returns the state (enabled/disabled) of the given extension.
+  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);
+
   // Returns base extensions install directory.
   const FilePath& install_directory() const { return install_directory_; }
 
@@ -73,6 +79,9 @@ class ExtensionPrefs {
   // Ensures and returns a mutable dictionary for extension |id|'s prefs.
   DictionaryValue* GetOrCreateExtensionPref(const std::string& id);
 
+  // Same as above, but returns NULL if it doesn't exist.
+  DictionaryValue* GetExtensionPref(const std::string& id);
+
   // Checks if kPrefBlacklist is set to true in the DictionaryValue.
   // Return false if the value is false or kPrefBlacklist does not exist.
   // This is used to decide if an extension is blacklisted.
@@ -106,6 +115,10 @@ class InstalledExtensions {
   // the callback.
   void VisitInstalledExtensions(Callback *callback);
 
+  // Same as above, but only for the given extension.
+  void VisitInstalledExtension(const std::string& extension_id,
+                               Callback *callback);
+
  private:
   // A copy of the extensions pref dictionary so that this can be passed
   // around without a dependency on prefs.
diff --git a/chrome/browser/extensions/extension_ui_unittest.cc b/chrome/browser/extensions/extension_ui_unittest.cc
index 022382b..f193b6a 100644
--- a/chrome/browser/extensions/extension_ui_unittest.cc
+++ b/chrome/browser/extensions/extension_ui_unittest.cc
@@ -44,13 +44,14 @@ namespace {
     EXPECT_TRUE(extension.InitFromValue(*extension_data, true, &error));
     EXPECT_EQ("", error);
 
-    scoped_ptr<DictionaryValue>expected_output_data(DeserializeJSONTestData(
+    scoped_ptr<DictionaryValue> expected_output_data(DeserializeJSONTestData(
         expected_output_path, &error));
     EXPECT_EQ("", error);
 
     // Produce test output.
     scoped_ptr<DictionaryValue> actual_output_data(
-        ExtensionsDOMHandler::CreateExtensionDetailValue(&extension, pages));
+        ExtensionsDOMHandler::CreateExtensionDetailValue(&extension, pages,
+                                                         true));
 
     // Compare the outputs.
     return expected_output_data->Equals(actual_output_data.get());
diff --git a/chrome/browser/extensions/extensions_service.cc b/chrome/browser/extensions/extensions_service.cc
index 70fa3db..f70d7cf 100644
--- a/chrome/browser/extensions/extensions_service.cc
+++ b/chrome/browser/extensions/extensions_service.cc
@@ -118,7 +118,7 @@ void ExtensionsService::InstallExtension(const FilePath& extension_path) {
 
 void ExtensionsService::UpdateExtension(const std::string& id,
                                         const FilePath& extension_path) {
-  if (!GetExtensionById(id)) {
+  if (!GetExtensionByIdInternal(id, true, true)) {
     LOG(WARNING) << "Will not update extension " << id << " because it is not "
                  << "installed";
     return;
@@ -142,7 +142,7 @@ void ExtensionsService::ReloadExtension(const std::string& extension_id) {
 
 void ExtensionsService::UninstallExtension(const std::string& extension_id,
                                            bool external_uninstall) {
-  Extension* extension = GetExtensionById(extension_id);
+  Extension* extension = GetExtensionByIdInternal(extension_id, true, true);
 
   // Callers should not send us nonexistant extensions.
   DCHECK(extension);
@@ -159,6 +159,29 @@ void ExtensionsService::UninstallExtension(const std::string& extension_id,
   UnloadExtension(extension_id);
 }
 
+void ExtensionsService::EnableExtension(const std::string& extension_id) {
+  Extension* extension = GetExtensionByIdInternal(extension_id, false, true);
+  if (!extension) {
+    NOTREACHED() << "Trying to enable an extension that isn't disabled.";
+    return;
+  }
+
+  // Move it over to the enabled list.
+  extension_prefs_->SetExtensionState(extension, Extension::ENABLED);
+  extensions_.push_back(extension);
+  ExtensionList::iterator iter = std::find(disabled_extensions_.begin(),
+                                           disabled_extensions_.end(),
+                                           extension);
+  disabled_extensions_.erase(iter);
+
+  ExtensionList extensions;
+  extensions.push_back(extension);
+  NotificationService::current()->Notify(
+      NotificationType::EXTENSIONS_LOADED,
+      Source<ExtensionsService>(this),
+      Details<ExtensionList>(&extensions));
+}
+
 void ExtensionsService::LoadExtension(const FilePath& extension_path) {
   backend_loop_->PostTask(FROM_HERE, NewRunnableMethod(backend_.get(),
       &ExtensionsServiceBackend::LoadSingleExtension,
@@ -213,17 +236,22 @@ void ExtensionsService::CheckForExternalUpdates() {
 }
 
 void ExtensionsService::UnloadExtension(const std::string& extension_id) {
-  Extension* extension = NULL;
-  ExtensionList::iterator iter;
-  for (iter = extensions_.begin(); iter != extensions_.end(); ++iter) {
-    if ((*iter)->id() == extension_id) {
-      extension = *iter;
-      break;
-    }
-  }
+  scoped_ptr<Extension> extension(
+      GetExtensionByIdInternal(extension_id, true, true));
 
   // Callers should not send us nonexistant extensions.
-  CHECK(extension);
+  CHECK(extension.get());
+
+  ExtensionList::iterator iter = std::find(disabled_extensions_.begin(),
+                                           disabled_extensions_.end(),
+                                           extension.get());
+  if (iter != disabled_extensions_.end()) {
+    // It's disabled, so don't send the unload notification.
+    disabled_extensions_.erase(iter);
+    return;
+  }
+
+  iter = std::find(extensions_.begin(), extensions_.end(), extension.get());
 
   // Remove the extension from our list.
   extensions_.erase(iter);
@@ -231,9 +259,7 @@ void ExtensionsService::UnloadExtension(const std::string& extension_id) {
   // Tell other services the extension is gone.
   NotificationService::current()->Notify(NotificationType::EXTENSION_UNLOADED,
                                          Source<ExtensionsService>(this),
-                                         Details<Extension>(extension));
-
-  delete extension;
+                                         Details<Extension>(extension.get()));
 }
 
 void ExtensionsService::UnloadAllExtensions() {
@@ -277,32 +303,56 @@ void ExtensionsService::OnExtensionsLoaded(ExtensionList* new_extensions) {
   // - --load-extension
   // - externally installed extensions
   ExtensionList enabled_extensions;
+  ExtensionList disabled_extensions;
   for (ExtensionList::iterator iter = new_extensions->begin();
        iter != new_extensions->end(); ++iter) {
+    // Extensions that get enabled get added to extensions_ and deleted later.
+    // Anything skipped must be deleted now so we don't leak.
+    scoped_ptr<Extension> extension(*iter);
     if (extensions_enabled() ||
-        (*iter)->IsTheme() ||
-        (*iter)->location() == Extension::LOAD ||
-        Extension::IsExternalLocation((*iter)->location())) {
-      Extension* old = GetExtensionById((*iter)->id());
+        extension->IsTheme() ||
+        extension->location() == Extension::LOAD ||
+        Extension::IsExternalLocation(extension->location())) {
+      Extension* old = GetExtensionById(extension->id());
       if (old) {
-        if ((*iter)->version()->CompareTo(*(old->version())) > 0) {
+        if (extension->version()->CompareTo(*(old->version())) > 0) {
+          bool higher_permissions =
+              (extension->GetPermissionClass() > old->GetPermissionClass());
+
           // To upgrade an extension in place, unload the old one and
           // then load the new one.
-          // TODO(erikkay) issue 12399
           UnloadExtension(old->id());
+          old = NULL;
+
+          if (higher_permissions) {
+            // Extension was upgraded to a high permission class. Disable it and
+            // notify the user.
+            extension_prefs_->SetExtensionState(extension.get(),
+                                                Extension::DISABLED);
+            NotificationService::current()->Notify(
+                NotificationType::EXTENSION_UPDATE_DISABLED,
+                Source<ExtensionsService>(this),
+                Details<Extension>(extension.get()));
+          }
         } else {
           // We already have the extension of the same or older version.
           LOG(WARNING) << "Duplicate extension load attempt: " << (*iter)->id();
-          delete *iter;
           continue;
         }
       }
-      enabled_extensions.push_back(*iter);
-      extensions_.push_back(*iter);
-    } else {
-      // Extensions that get enabled get added to extensions_ and deleted later.
-      // Anything skipped must be deleted now so we don't leak.
-      delete *iter;
+
+      switch (extension_prefs_->GetExtensionState(extension->id())) {
+        case Extension::ENABLED:
+          enabled_extensions.push_back(extension.get());
+          extensions_.push_back(extension.release());
+          break;
+        case Extension::DISABLED:
+          disabled_extensions.push_back(extension.get());
+          disabled_extensions_.push_back(extension.release());
+          break;
+        default:
+          break;
+      }
     }
   }
 
@@ -346,7 +396,6 @@ void ExtensionsService::OnExtensionInstalled(Extension* extension) {
   OnExtensionsLoaded(list);
 }
 
-
 void ExtensionsService::OnExtensionOverinstallAttempted(const std::string& id) {
   Extension* extension = GetExtensionById(id);
   if (extension && extension->IsTheme()) {
@@ -357,12 +406,23 @@ void ExtensionsService::OnExtensionOverinstallAttempted(const std::string& id) {
   }
 }
 
-Extension* ExtensionsService::GetExtensionById(const std::string& id) {
+Extension* ExtensionsService::GetExtensionByIdInternal(const std::string& id,
+                                                       bool include_enabled,
+                                                       bool include_disabled) {
   std::string lowercase_id = StringToLowerASCII(id);
-  for (ExtensionList::const_iterator iter = extensions_.begin();
-      iter != extensions_.end(); ++iter) {
-    if ((*iter)->id() == lowercase_id)
-      return *iter;
+  if (include_enabled) {
+    for (ExtensionList::const_iterator iter = extensions_.begin();
+        iter != extensions_.end(); ++iter) {
+      if ((*iter)->id() == lowercase_id)
+        return *iter;
+    }
+  }
+  if (include_disabled) {
+    for (ExtensionList::const_iterator iter = disabled_extensions_.begin();
+        iter != disabled_extensions_.end(); ++iter) {
+      if ((*iter)->id() == lowercase_id)
+        return *iter;
+    }
   }
   return NULL;
 }
diff --git a/chrome/browser/extensions/extensions_service.h b/chrome/browser/extensions/extensions_service.h
index fe0a545..fafe97e 100644
--- a/chrome/browser/extensions/extensions_service.h
+++ b/chrome/browser/extensions/extensions_service.h
@@ -87,8 +87,9 @@ class ExtensionsService
   virtual ~ExtensionsService();
 
   // Gets the list of currently installed extensions.
-  virtual const ExtensionList* extensions() const {
-    return &extensions_;
+  virtual const ExtensionList* extensions() const { return &extensions_; }
+  virtual const ExtensionList* disabled_extensions() const {
+    return &disabled_extensions_;
   }
 
   const FilePath& install_directory() const { return install_directory_; }
@@ -96,6 +97,11 @@ class ExtensionsService
   // Initialize and start all installed extensions.
   void Init();
 
+  // Look up an extension by ID.
+  Extension* GetExtensionById(const std::string& id) {
+    return GetExtensionByIdInternal(id, true, false);
+  }
+
   // Install the extension file at |extension_path|.  Will install as an
   // update if an older version is already installed.
   // For fresh installs, this method also causes the extension to be
@@ -123,6 +129,11 @@ class ExtensionsService
   void UninstallExtension(const std::string& extension_id,
                           bool external_uninstall);
 
+  // Enable a previously disabled extension and reload it. The extension should
+  // already exist in the extension prefs.
+  // TODO(mpcomplete): add DisableExtension.
+  void EnableExtension(const std::string& extension_id);
+
   // Load the extension from the directory |extension_path|.
   void LoadExtension(const FilePath& extension_path);
 
@@ -144,9 +155,6 @@ class ExtensionsService
   // Scan the extension directory and clean up the cruft.
   void GarbageCollectExtensions();
 
-  // Lookup an extension by |id|.
-  virtual Extension* GetExtensionById(const std::string& id);
-
   // Lookup an extension by |url|.  This uses the host of the URL as the id.
   Extension* GetExtensionByURL(const GURL& url);
 
@@ -202,6 +210,12 @@ class ExtensionsService
   bool is_ready() { return ready_; }
 
  private:
+  // 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);
+
   // The profile this ExtensionsService is part of.
   Profile* profile_;
 
@@ -214,6 +228,9 @@ class ExtensionsService
   // The current list of installed extensions.
   ExtensionList extensions_;
 
+  // The list of installed extensions that have been disabled.
+  ExtensionList disabled_extensions_;
+
   // The full path to the directory where extensions are installed.
   FilePath install_directory_;
 
diff --git a/chrome/browser/extensions/extensions_ui.cc b/chrome/browser/extensions/extensions_ui.cc
index 849fc8f..126fa05 100644
--- a/chrome/browser/extensions/extensions_ui.cc
+++ b/chrome/browser/extensions/extensions_ui.cc
@@ -77,6 +77,8 @@ void ExtensionsDOMHandler::RegisterMessages() {
       NewCallback(this, &ExtensionsDOMHandler::HandleInspectMessage));
   dom_ui_->RegisterMessageCallback("reload",
       NewCallback(this, &ExtensionsDOMHandler::HandleReloadMessage));
+  dom_ui_->RegisterMessageCallback("enable",
+      NewCallback(this, &ExtensionsDOMHandler::HandleEnableMessage));
   dom_ui_->RegisterMessageCallback("uninstall",
       NewCallback(this, &ExtensionsDOMHandler::HandleUninstallMessage));
 }
@@ -93,7 +95,15 @@ void ExtensionsDOMHandler::HandleRequestExtensionsData(const Value* value) {
     // themes.
     if (!(*extension)->IsTheme()) {
       extensions_list->Append(CreateExtensionDetailValue(
-          *extension, GetActivePagesForExtension((*extension)->id())));
+          *extension, GetActivePagesForExtension((*extension)->id()), true));
+    }
+  }
+  extensions = extensions_service_->disabled_extensions();
+  for (ExtensionList::const_iterator extension = extensions->begin();
+       extension != extensions->end(); ++extension) {
+    if (!(*extension)->IsTheme()) {
+      extensions_list->Append(CreateExtensionDetailValue(
+          *extension, GetActivePagesForExtension((*extension)->id()), false));
     }
   }
   results.Set(L"extensions", extensions_list);
@@ -132,6 +142,15 @@ void ExtensionsDOMHandler::HandleReloadMessage(const Value* value) {
   extensions_service_->ReloadExtension(extension_id);
 }
 
+void ExtensionsDOMHandler::HandleEnableMessage(const Value* value) {
+  CHECK(value->IsType(Value::TYPE_LIST));
+  const ListValue* list = static_cast<const ListValue*>(value);
+  CHECK(list->GetSize() == 1);
+  std::string extension_id;
+  CHECK(list->GetString(0, &extension_id));
+  extensions_service_->EnableExtension(extension_id);
+}
+
 void ExtensionsDOMHandler::HandleUninstallMessage(const Value* value) {
   CHECK(value->IsType(Value::TYPE_LIST));
   const ListValue* list = static_cast<const ListValue*>(value);
@@ -187,13 +206,15 @@ DictionaryValue* ExtensionsDOMHandler::CreateContentScriptDetailValue(
 
 // Static
 DictionaryValue* ExtensionsDOMHandler::CreateExtensionDetailValue(
-    const Extension *extension, const std::vector<ExtensionPage>& pages) {
+    const Extension *extension, const std::vector<ExtensionPage>& pages,
+    bool enabled) {
   DictionaryValue* extension_data = new DictionaryValue();
 
   extension_data->SetString(L"id", extension->id());
   extension_data->SetString(L"name", extension->name());
   extension_data->SetString(L"description", extension->description());
   extension_data->SetString(L"version", extension->version()->GetString());
+  extension_data->SetBoolean(L"enabled", enabled);
 
   // Add list of content_script detail DictionaryValues
   ListValue *content_script_list = new ListValue();
diff --git a/chrome/browser/extensions/extensions_ui.h b/chrome/browser/extensions/extensions_ui.h
index c92c2ca..b63b12b 100644
--- a/chrome/browser/extensions/extensions_ui.h
+++ b/chrome/browser/extensions/extensions_ui.h
@@ -57,7 +57,8 @@ class ExtensionsDOMHandler : public DOMMessageHandler {
   // Extension Detail JSON Struct for page. (static for ease of testing).
   static DictionaryValue* CreateExtensionDetailValue(
       const Extension *extension,
-      const std::vector<ExtensionPage>&);
+      const std::vector<ExtensionPage>&,
+      bool enabled);
 
   // ContentScript JSON Struct for page. (static for ease of testing).
   static DictionaryValue* CreateContentScriptDetailValue(
@@ -74,6 +75,9 @@ class ExtensionsDOMHandler : public DOMMessageHandler {
   // Callback for "reload" message.
   void HandleReloadMessage(const Value* value);
 
+  // Callback for "enable" message.
+  void HandleEnableMessage(const Value* value);
+
   // Callback for "uninstall" message.
   void HandleUninstallMessage(const Value* value);
 
diff --git a/chrome/browser/resources/extensions_ui.html b/chrome/browser/resources/extensions_ui.html
index 8cd383c..566a989 100644
--- a/chrome/browser/resources/extensions_ui.html
+++ b/chrome/browser/resources/extensions_ui.html
@@ -15,6 +15,7 @@ var extensionDataFormat = {
       "name": "Extension Name",
       "description": "Extension long format description",
       "version": "1.0.231",
+      "enabled": "true",
       "content_scripts": [
         {
           "js": ["script1_file1.js", "script1_file2.js"],
@@ -49,6 +50,7 @@ var extensionDataFormat = {
       "name": "Extension Name",
       "description": "Extension long format description",
       "version": "1.0.231",
+      "enabled": "true",
       "content_scripts": [
         {
           "js": ["script1_file1.js", "script1_file2.js"],
@@ -129,6 +131,15 @@ function handleReloadExtension(node) {
 }
 
 /**
+ * Handles a 'reenable' button getting clicked.
+ */
+function handleEnableExtension(node) {
+  // Tell the C++ ExtensionDOMHandler to reload the extension.
+  chrome.send('enable', [node.extensionId]);
+  requestExtensionsData();
+}
+
+/**
  * Handles an 'uninstall' button getting clicked.
  */
 function handleUninstallExtension(node) {
@@ -247,10 +258,19 @@ th.desc {
 
         <div jsdisplay="extensions.length > 0">
           <div class="extension" jsselect="extensions">
-            <div class="extension-name" jscontent="name">Extension Name</div>
+            <div class="extension-name">
+              <span jscontent="name">Extension Name</span>
+              <span jsdisplay="!enabled">(Disabled)</span>
+            </div>
             <div class="extension-actions">
               <button
                 jsvalues=".extensionId:id"
+                jsdisplay="!enabled"
+                onclick="handleEnableExtension(this)"
+                >Enable</button>
+              <button
+                jsvalues=".extensionId:id"
+                jsdisplay="enabled"
                 onclick="handleReloadExtension(this)"
                 >Reload</button>
               <button
diff --git a/chrome/chrome.gyp b/chrome/chrome.gyp
index 74839ad..2f17cf7 100644
--- a/chrome/chrome.gyp
+++ b/chrome/chrome.gyp
@@ -1001,6 +1001,8 @@
         'browser/extensions/extension_bookmarks_module_constants.h',
         'browser/extensions/extension_creator.cc',
         'browser/extensions/extension_creator.h',
+        'browser/extensions/extension_disabled_infobar_delegate.cc',
+        'browser/extensions/extension_disabled_infobar_delegate.h',
         'browser/extensions/extension_dom_ui.cc',
         'browser/extensions/extension_dom_ui.h',
         'browser/extensions/extension_event_names.cc',
diff --git a/chrome/common/extensions/extension.h b/chrome/common/extensions/extension.h
index 5bcc456..b9761d0 100644
--- a/chrome/common/extensions/extension.h
+++ b/chrome/common/extensions/extension.h
@@ -33,9 +33,11 @@ class Extension {
   };
 
   enum State {
-    DISABLED,
+    DISABLED = 0,
     ENABLED,
     KILLBIT,  // Don't install/upgrade (applies to external extensions only).
+
+    NUM_STATES
   };
 
   enum InstallType {
diff --git a/chrome/common/notification_type.h b/chrome/common/notification_type.h
index 2a04ffe..8ba2d84 100644
--- a/chrome/common/notification_type.h
+++ b/chrome/common/notification_type.h
@@ -603,6 +603,10 @@ class NotificationType {
     // Sent when new extensions are loaded. The details are an ExtensionList*.
     EXTENSIONS_LOADED,
 
+    // Sent when attempting to load a new extension, but they are disabled. The
+    // details are an Extension*.
+    EXTENSION_UPDATE_DISABLED,
+
     // Sent when a new theme is installed. The details are an Extension.
     THEME_INSTALLED,
 
diff --git a/chrome/test/data/extensions/permissions-high-v2.crx b/chrome/test/data/extensions/permissions-high-v2.crx
new file mode 100755
index 0000000..3dd4959
--- /dev/null
+++ b/chrome/test/data/extensions/permissions-high-v2.crx
diff --git a/chrome/test/data/extensions/permissions-low-v1.crx b/chrome/test/data/extensions/permissions-low-v1.crx
new file mode 100755
index 0000000..fbea4d0
--- /dev/null
+++ b/chrome/test/data/extensions/permissions-low-v1.crx
diff --git a/chrome/test/data/extensions/permissions-low-v1.pem b/chrome/test/data/extensions/permissions-low-v1.pem
new file mode 100755
index 0000000..c875aca
--- /dev/null
+++ b/chrome/test/data/extensions/permissions-low-v1.pem
@@ -0,0 +1,16 @@
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----
diff --git a/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension1.json b/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension1.json
index 6c50242..91d1ca8 100644
--- a/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension1.json
+++ b/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension1.json
@@ -2,6 +2,7 @@
   "id": "behllobkkfkfnphdnhnkndlbkcpglgmj",
   "version": "1.0.0.0",
   "name": "My extension 1",
+  "enabled": true,
   "description": "The first extension that I made.",
   "permissions": ["http://*.google.com/*", "https://*.google.com/*"],
   "content_scripts": [
diff --git a/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension2.json b/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension2.json
index 63ea47a..807b5d0 100644
--- a/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension2.json
+++ b/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension2.json
@@ -2,6 +2,7 @@
   "id": "hpiknbiabeeppbpihjehijgoemciehgk",
   "version": "2",
   "name": "My extension 2",
+  "enabled": true,
   "description": "",
   "permissions": [],
   "content_scripts": [],
diff --git a/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension3.json b/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension3.json
index a444d4b..fef5a50 100644
--- a/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension3.json
+++ b/chrome/test/data/extensions/ui/create_extension_detail_value_expected_output/good-extension3.json
@@ -2,6 +2,7 @@
   "id": "bjafgdebaacbbbecmhlhpofkepfkgcpa",
   "version": "1.0",
   "name": "My extension 3",
+  "enabled": true,
   "description": "",
   "permissions": [],
   "content_scripts": [