Enable range-based for loops to loop over a WebContents' frame hosts.

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index f7f09b79f98dec0e6286128d743c7d0ecfa32803..5260b915adc056f9ec8db414afb2f504e989664a 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -228,6 +228,10 @@ class WebContents : public PageNavigator,
   virtual void ForEachFrame(
       const base::Callback<void(RenderFrameHost*)>& on_frame) = 0;
 
+  // Returns a vector of all RenderFrameHosts in the currently active view in
+  // breadth-first traversal order.
+  virtual std::vector<RenderFrameHost*> GetAllFrames() = 0;
+
   // Sends the given IPC to all frames in the currently active view and returns
   // the number of sent messages (i.e. the number of processed frames). This is
   // a convenience method instead of calling ForEach.