override chrome:// URLs via extensions.

Overrides are declared in an extension's manifest.  The last one installed
wins.  However, we keep a list of those installed per page so that priority
is preserved and so that uninstall will revert to a previous state.

Review URL: http://codereview.chromium.org/174277

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@24791 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 45 insertions, 0 deletions

diff --git a/chrome/common/extensions/extension.cc b/chrome/common/extensions/extension.cc
index c826c07..3f3c8539 100644
--- a/chrome/common/extensions/extension.cc
+++ b/chrome/common/extensions/extension.cc
@@ -998,6 +998,37 @@ bool Extension::InitFromValue(const DictionaryValue& source, bool require_id,
     set_default_locale(default_locale);
   }
 
+  // Chrome URL overrides (optional)
+  if (source.HasKey(keys::kChromeURLOverrides)) {
+    DictionaryValue* overrides;
+    if (!source.GetDictionary(keys::kChromeURLOverrides, &overrides)) {
+      *error = errors::kInvalidChromeURLOverrides;
+      return false;
+    }
+    // Validate that the overrides are all strings
+    DictionaryValue::key_iterator iter = overrides->begin_keys();
+    while (iter != overrides->end_keys()) {
+      // For now, only allow the new tab page.  Others will work when we remove
+      // this check, but let's keep it simple for now.
+      // TODO(erikkay) enable other pages as well
+      if (WideToUTF8(*iter) != chrome::kChromeUINewTabHost) {
+        *error = errors::kInvalidChromeURLOverrides;
+        return false;
+      }
+      std::string val;
+      if (!overrides->GetString(*iter, &val)) {
+        *error = errors::kInvalidChromeURLOverrides;
+        return false;
+      }
+      // Replace the entry with a fully qualified chrome-extension:// URL.
+      GURL url = GetResourceURL(val);
+      overrides->SetString(*iter, url.spec());
+      ++iter;
+    }
+    chrome_url_overrides_.reset(
+        static_cast<DictionaryValue*>(overrides->DeepCopy()));
+  }
+
   return true;
 }
 
diff --git a/chrome/common/extensions/extension.h b/chrome/common/extensions/extension.h
index 6e7215f..e8cdd10 100644
--- a/chrome/common/extensions/extension.h
+++ b/chrome/common/extensions/extension.h
@@ -262,6 +262,11 @@ class Extension {
     default_locale_ = default_locale;
   }
 
+  // Chrome URL overrides (see ExtensionOverrideUI).
+  DictionaryValue* GetChromeURLOverrides() const {
+    return chrome_url_overrides_.get();
+  }
+
   // Runtime data:
   // Put dynamic data about the state of a running extension below.
 
@@ -382,6 +387,10 @@ class Extension {
   // Default locale, used for fallback.
   std::string default_locale_;
 
+  // A map of chrome:// hostnames (newtab, downloads, etc.) to Extension URLs
+  // which override the handling of those URLs.
+  scoped_ptr<DictionaryValue> chrome_url_overrides_;
+
   // Runtime data:
 
   // True if the background page is ready.
diff --git a/chrome/common/extensions/extension_constants.cc b/chrome/common/extensions/extension_constants.cc
index d887678..d72fbcf 100644
--- a/chrome/common/extensions/extension_constants.cc
+++ b/chrome/common/extensions/extension_constants.cc
@@ -7,6 +7,7 @@
 namespace extension_manifest_keys {
 
 const wchar_t* kBackground = L"background_page";
+const wchar_t* kChromeURLOverrides = L"chrome_url_overrides";
 const wchar_t* kContentScripts = L"content_scripts";
 const wchar_t* kCss = L"css";
 const wchar_t* kDefaultLocale = L"default_locale";
@@ -52,6 +53,8 @@ const char* kPageActionTypePermanent = "permanent";
 // printf because we want to unit test them and scanf is hard to make
 // cross-platform.
 namespace extension_manifest_errors {
+const char* kInvalidChromeURLOverrides =
+    "Invalid value for 'chrome_url_overrides'.";
 const char* kInvalidContentScript =
     "Invalid value for 'content_scripts[*]'.";
 const char* kInvalidContentScriptsList =
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index b808665..09429a2 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -8,6 +8,7 @@
 // Keys used in JSON representation of extensions.
 namespace extension_manifest_keys {
   extern const wchar_t* kBackground;
+  extern const wchar_t* kChromeURLOverrides;
   extern const wchar_t* kContentScripts;
   extern const wchar_t* kCss;
   extern const wchar_t* kDefaultLocale;
@@ -51,6 +52,7 @@ namespace extension_manifest_values {
 
 // Error messages returned from Extension::InitFromValue().
 namespace extension_manifest_errors {
+  extern const char* kInvalidChromeURLOverrides;
   extern const char* kInvalidContentScript;
   extern const char* kInvalidContentScriptsList;
   extern const char* kInvalidCss;