[Extensions Toolbar] Add a finch config for the redesign

chrome/browser/extensions/extension_action.h

Index: chrome/browser/extensions/extension_action.h
diff --git a/chrome/browser/extensions/extension_action.h b/chrome/browser/extensions/extension_action.h
index 9e73dbc9e0a2564c82742906a0d3c48a0355aff8..01385f830466af94e514507afd5d4e125267edf9 100644
--- a/chrome/browser/extensions/extension_action.h
+++ b/chrome/browser/extensions/extension_action.h
@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "chrome/common/extensions/api/extension_action/action_info.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "ui/gfx/image/image.h"
 
 class GURL;
 
@@ -287,6 +288,10 @@ class ExtensionAction {
   // Lazily initialized via LoadDefaultIconImage().
   scoped_ptr<extensions::IconImage> default_icon_image_;
 
+  // The lazily-initialized image for a placeholder icon, in the event that the
+  // extension doesn't have its own icon. (Mutable to allow lazy init.)

[Finnur, 2015/09/22 14:18:32]

... to allow lazy init in GetDefaultIconImage.

[Devlin, 2015/09/23 00:28:35]

Done.

+  mutable gfx::Image placeholder_icon_image_;
+
   // The id for the ExtensionAction, for example: "RssPageAction". This is
   // needed for compat with an older version of the page actions API.
   std::string id_;