Adding OverrideStringResource API to ResourceBundle.

ui/base/resource/resource_bundle.h

Index: ui/base/resource/resource_bundle.h
diff --git a/ui/base/resource/resource_bundle.h b/ui/base/resource/resource_bundle.h
index 809b1125159ef939b2cbddb450b36f9f7ed57da4..ef006a8969e96511c66a1c175b57c5488527fbce 100644
--- a/ui/base/resource/resource_bundle.h
+++ b/ui/base/resource/resource_bundle.h
@@ -9,6 +9,7 @@
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/containers/hash_tables.h"
 #include "base/files/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
@@ -245,6 +246,15 @@ class UI_BASE_EXPORT ResourceBundle {
   // loaded. Pass an empty path to undo.
   void OverrideLocalePakForTest(const base::FilePath& pak_path);
 
+  // Overrides a localized string resource with the given string. If no delegate
+  // is present, the |string| will be returned when getting the localized string
+  // |message_id|. If |ReloadLocaleResources| is called, all overrides are
+  // cleared. This is intended to be used in conjunction with field trials and
+  // the variations service to experiment with different UI strings. This method
+  // is not thread safe!
+  void OverrideLocaleStringResource(int message_id,

[grt (UTC plus 2), 2014/07/03 19:00:34]

how will this be used so that it's safe?

[jwd, 2014/07/11 19:23:27]

It's only used in prethreadcreate...
It's only called though SetupMetricsAndFieldTrials which is called from
ChromeBrowserMainParts::PreCreateThreadsImpl.

+                                    const base::string16& string);
+
   // Returns the full pathname of the locale file to load.  May return an empty
   // string if no locale data files are found and |test_file_exists| is true.
   // Used on Android to load the local file in the browser process and pass it
@@ -267,6 +277,8 @@ class UI_BASE_EXPORT ResourceBundle {
   class ResourceBundleImageSource;
   friend class ResourceBundleImageSource;
 
+  typedef base::hash_map<int, base::string16> IdToStringMap;
+
   // Ctor/dtor are private, since we're a singleton.
   explicit ResourceBundle(Delegate* delegate);
   ~ResourceBundle();
@@ -391,6 +403,8 @@ class UI_BASE_EXPORT ResourceBundle {
 
   base::FilePath overridden_pak_path_;
 
+  IdToStringMap overridden_locale_strings_;
+
   DISALLOW_COPY_AND_ASSIGN(ResourceBundle);
 };