Add new ResourceBundle::Delegate interface.

ui/base/resource/resource_bundle.h

Index: ui/base/resource/resource_bundle.h
===================================================================
--- ui/base/resource/resource_bundle.h	(revision 133962)
+++ ui/base/resource/resource_bundle.h	(working copy)
@@ -63,12 +63,58 @@
     RTL_DISABLED,
   };
 
-  // Initialize the ResourceBundle for this process.  Returns the language
-  // selected.
+  class Delegate {
+   public:
+    // Retrieve the full path for the specified |pack_name|. |pack_path| will
+    // initially contain the default path for the pack file. Change it in this
+    // callback if a different path is desired. Return true to continue loading
+    // the pack file or false to cancel the load.
+    virtual bool GetPathForResourcePack(const std::string& pack_name,
+                                        FilePath* pack_path) = 0;
+
+    // Retrieve the full path for the specified |locale|. |pack_path| will
+    // initially contain the default path for the pack file. Change it in this
+    // callback if a different path is desired. Return true to continue loading
+    // the pack file or false to cancel the load.
+    virtual bool GetPathForLocalePack(const std::string& locale,
+                                      FilePath* pack_path) = 0;
+
+    // Return an image resource or NULL to attempt retrieval of the default
+    // resource. The returned value will be owned by ResourceBundle.
+    virtual gfx::Image* GetImageNamed(int resource_id) = 0;

[sail, 2012/04/30 21:14:43]

can you have this return a scoped_ptr. Then you can get rid of the comment about
ownership. Same below.

[Marshall, 2012/04/30 21:50:10]

Done.

+
+    // Return an image resource or NULL to attempt retrieval of the default
+    // resource. The returned value will be owned by ResourceBundle.
+    virtual gfx::Image* GetNativeImageNamed(int resource_id, ImageRTL rtl) = 0;
+
+    // Return a static memory resource or NULL to attempt retrieval of the
+    // default resource.
+    virtual base::RefCountedStaticMemory* LoadDataResourceBytes(
+        int resource_id) = 0;
+
+    // Retrieve a raw data resource. Return true if a resource was provided or
+    // false to attempt retrieval of the default resource.
+    virtual bool GetRawDataResource(int resource_id,
+                                    base::StringPiece* value) = 0;
+
+    // Retrieve a localized string. Return true if a string was provided or
+    // false to attempt retrieval of the default string.
+    virtual bool GetLocalizedString(int message_id, string16* value) = 0;
+
+    // Return a font resource or NULL to attempt retrieval of the default
+    // resource. The returned value will be owned by ResourceBundle.
+    virtual gfx::Font* GetFont(FontStyle style) = 0;
+
+   protected:
+    virtual ~Delegate() {}
+  };
+
+  // Initialize the ResourceBundle for this process. Does not take ownership of
+  // the |delegate| value. Returns the language selected.
   // NOTE: Mac ignores this and always loads up resources for the language
   // defined by the Cocoa UI (i.e., NSBundle does the language work).
   static std::string InitSharedInstanceWithLocale(
-      const std::string& pref_locale);
+      const std::string& pref_locale, Delegate* delegate);
 
   // Initialize the ResourceBundle using given data pack path for testing.
   static void InitSharedInstanceWithPakFile(const FilePath& path);
@@ -83,7 +129,7 @@
   static ResourceBundle& GetSharedInstance();
 
   // Check if the .pak for the given locale exists.
-  static bool LocaleDataPakExists(const std::string& locale);
+  bool LocaleDataPakExists(const std::string& locale);
 
   // Registers additional data pack files with the global ResourceBundle.  When
   // looking for a DataResource, we will search these files after searching the
@@ -151,7 +197,7 @@
   FRIEND_TEST_ALL_PREFIXES(ResourceBundle, LoadDataResourceBytes);
 
   // Ctor/dtor are private, since we're a singleton.
-  ResourceBundle();
+  explicit ResourceBundle(Delegate* delegate);
   ~ResourceBundle();
 
   // Free skia_images_.
@@ -160,6 +206,10 @@
   // Load the main resources.
   void LoadCommonResources();
 
+  // Add a common data pack to the ResourceBundle. Gives the delegate an
+  // opportunity to modify the load.
+  void AddCommonDataPack(const std::string& pack_name, const FilePath& path);

[sail, 2012/04/30 21:14:43]

do you really need AddDataPack and AddCommonDataPack? Can we just have one?

If both are necessary then can you add a comment in both places about when one
should be used and when the other should be used.

[Marshall, 2012/04/30 21:50:10]

I think both are needed. AddDataPack() is used external to ResourceBundle to
load pack files after the ResourceBundle is created and does not trigger the
delegate. AddCommonDataPack() is used in ResourceBundle::LoadCommonResources()
and allows the delegate to override. The comments should make that clearer now.

[sail, 2012/04/30 22:33:26]

But why does external vs internal matter? Why wouldn't external AddDataPack()
requests get routed through the delegate?

[Marshall, 2012/05/01 17:29:41]

Removed the additional method.

+
   // Try to load the locale specific strings from an external data module.
   // Returns the locale that is loaded.
   std::string LoadLocaleResources(const std::string& pref_locale);
@@ -176,7 +226,7 @@
 
   // Returns the full pathname of the locale file to load.  May return an empty
   // string if no locale data files are found.
-  static FilePath GetLocaleFilePath(const std::string& app_locale);
+  FilePath GetLocaleFilePath(const std::string& app_locale);
 
   // Creates and returns a new SkBitmap given the data file to look in and the
   // resource id.  It's up to the caller to free the returned bitmap when
@@ -189,6 +239,9 @@
 
   const FilePath& GetOverriddenPakPath();
 
+  // This pointer is guaranteed to outlive the ResourceBundle instance.
+  Delegate* delegate_;
+
   // Protects |images_| and font-related members.
   scoped_ptr<base::Lock> images_and_fonts_lock_;