Add new extension APIs related to animation policy.

content/public/browser/browser_accessibility_state.h

Index: content/public/browser/browser_accessibility_state.h
diff --git a/content/public/browser/browser_accessibility_state.h b/content/public/browser/browser_accessibility_state.h
index 6c91e1b7b7699734675ebe734dba84c711e96fea..6a2ead27f1ec370991945ae22e253075e87aa116 100644
--- a/content/public/browser/browser_accessibility_state.h
+++ b/content/public/browser/browser_accessibility_state.h
@@ -39,6 +39,13 @@ class CONTENT_EXPORT BrowserAccessibilityState {
   // Returns true if the browser should be customized for accessibility.
   virtual bool IsAccessibleBrowser() = 0;
 
+  // Gets the policy for handling animated images.
+  // It has three options, "Allowed", "Once" and "None".
+  virtual const std::string& GetImageAnimationPolicy() const = 0;
+
+  // Sets the policy for handling animated images.
+  virtual void SetImageAnimationPolicy(const std::string& policy) = 0;
+
   // Add a callback method that will be called once, a small while after the
   // browser starts up, when accessibility state histograms are updated.
   // Use this to register a method to update additional accessibility