move favicon download code from chrome/ into content/

content/public/browser/web_contents_observer.h

Index: content/public/browser/web_contents_observer.h
diff --git a/content/public/browser/web_contents_observer.h b/content/public/browser/web_contents_observer.h
index 87f5f7e2cc27117b65d464f0e83f83442803b00f..a037efb70a67e021af4dd95794684f557affd038 100644
--- a/content/public/browser/web_contents_observer.h
+++ b/content/public/browser/web_contents_observer.h
@@ -19,6 +19,7 @@ namespace content {
 class RenderViewHost;
 class WebContents;
 class WebContentsImpl;
+struct FaviconURL;
 struct FrameNavigateParams;
 struct LoadCommittedDetails;
 struct Referrer;
@@ -142,6 +143,10 @@ class CONTENT_EXPORT WebContentsObserver : public IPC::Listener,
   virtual void DidBlock3DAPIs(const GURL& url,
                               ThreeDAPIType requester) {}
 
+  // Invoked when new FaviconURL candidates are received from the renderer.
+  virtual void DidUpdateFaviconURL(int32 page_id,
+                                   const std::vector<FaviconURL>& candidates) {}
+
   // IPC::Listener implementation.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;