Add new extension APIs related to animation policy.

content/browser/web_contents/web_contents_impl.h

Index: content/browser/web_contents/web_contents_impl.h
diff --git a/content/browser/web_contents/web_contents_impl.h b/content/browser/web_contents/web_contents_impl.h
index 8e1c65719186c10b67c940f7db1b2df4e72556b3..7f701e614a749c57341d05453b260b6c7c594a95 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -196,6 +196,9 @@ class CONTENT_EXPORT WebContentsImpl
   // from a native app.
   void ClearNavigationTransitionData();
 
+  // Set the policy for handling animated images
+  void SetImageAnimationPolicy(const std::string& policy);

[dmazzoni, 2014/12/08 07:46:01]

There should be an enum defined somewhere in Chromium code for this rather than
passing a string around.

Use a string only for the JavaScript API, everywhere else use an enum.

+
   // WebContents ------------------------------------------------------
   WebContentsDelegate* GetDelegate() override;
   void SetDelegate(WebContentsDelegate* delegate) override;