Change browser/page action default icon defined in manifest to support hidpi.

chrome/common/extensions/extension_icon_factory_delegate.h

Index: chrome/common/extensions/extension_icon_factory_delegate.h
diff --git a/chrome/common/extensions/extension_icon_factory_delegate.h b/chrome/common/extensions/extension_icon_factory_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..8ecd56362468a659c1f801f6aa3cbdb636f5ff80
--- /dev/null
+++ b/chrome/common/extensions/extension_icon_factory_delegate.h
@@ -0,0 +1,26 @@
+// Copyright (c) 2012 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_COMMON_EXTENSIONS_EXTENSION_ICON_FACTORY_DELEGATE_H_
+#define CHROME_COMMON_EXTENSIONS_EXTENSION_ICON_FACTORY_DELEGATE_H_
+
+#include "chrome/common/extensions/extension_icon_set.h"
+
+namespace gfx {
+class ImageSkia;
+}
+
+// Used by code living in chrome/common/ to delegate icon creation when the icon
+// creation cannot be done from chrome/common/ (e.g. if the icon is loaded
+// asynchronously using ImageLoadingTracker).
+class ExtensionIconFactoryDelegate {
+ public:
+  virtual ~ExtensionIconFactoryDelegate() {}
+
+  // Should create icon of desired size from icon paths defined in |icon_set|.
+  virtual gfx::ImageSkia GetIcon(const ExtensionIconSet* icon_set,
+                                 int desired_size) = 0;

[Jeffrey Yasskin, 2012/09/13 00:23:36]

Still trying to get my head around the meaning of this class ... I think what
this does is provide a way to load an icon of a given
gfx::Size-in-device-independent-pixels, given a set of icon paths for various
scales. Is that correct? If so, please include that in the comments. I think it
could make sense to pass gfx::Size instead of an int, even though all extension
icons are currently square.

Since these are paths and not pre-loaded images, any use of this class will
require an observer, but the observer is hidden away in browser/ with no
reference from here. It would be nice to make the returned object observable
directly, but if that's infeasible, I'd like some place to document the overall
arrangement of objects.

[tbarzic, 2012/09/13 02:01:01]

Done.

+};
+
+#endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_ICON_FACTORY_DELEGATE_H_