Add Observer in FaviconTabHelper

components/favicon/core/favicon_driver.h

 // Copyright 2014 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 COMPONENTS_FAVICON_CORE_FAVICON_DRIVER_H_
 #define COMPONENTS_FAVICON_CORE_FAVICON_DRIVER_H_
 
 class GURL;
 
 namespace gfx {
@@ skipping 43 matching lines @@
   // Sets the bitmap of the current page's favicon. Requires GetActiveURL() to
   // be valid.
   virtual void SetActiveFaviconImage(gfx::Image image) = 0;
 
   // Sets the URL of the favicon's bitmap. Requires GetActiveURL() to be valid.
   virtual void SetActiveFaviconURL(GURL url) = 0;
 
   // Sets whether the page's favicon is valid (if false, the default favicon is
   // being used). Requires GetActiveURL() to be valid.
   virtual void SetActiveFaviconValidity(bool validity) = 0;
+
+  // Notifies the driver favicon |image| is available to use.
+  virtual void OnFaviconAvailable(const gfx::Image& image) = 0;

[sky, 2014/10/30 03:34:31]

Can we leave the FaviconHandler as it was, meaning calling into
SetActiveFaviconImage and instead make FaviconTabHelper take a boolean as to
whether it should push to NavigationEntry or not? In either can it notifies the
observer.

[michaelbai, 2014/10/30 19:22:50]

Let me know if you are happy with new patch.

 };
 
 #endif  // COMPONENTS_FAVICON_CORE_FAVICON_DRIVER_H_