Remove the is_loading_ field from WebContentsImpl

content/browser/frame_host/frame_tree.h

 // Copyright 2013 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 CONTENT_BROWSER_FRAME_HOST_FRAME_TREE_H_
 #define CONTENT_BROWSER_FRAME_HOST_FRAME_TREE_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 136 matching lines @@
   // Updates the overall load progress and notifies the WebContents.
   void UpdateLoadProgress();
 
   // Returns this FrameTree's total load progress.
   double load_progress() { return load_progress_; }
 
   // Resets the load progress on all nodes in this FrameTree.
   void ResetLoadProgress();
 
   // Returns true if at least one of the nodes in this FrameTree is loading.
-  bool IsLoading();
+  bool IsLoading() const;
 
   // Set page-level focus in all SiteInstances involved in rendering
   // this FrameTree, not including the current main frame's
   // SiteInstance. The focus update will be sent via the main frame's proxies
   // in those SiteInstances.
   void ReplicatePageFocus(bool is_focused);
 
   // Updates page-level focus for this FrameTree in the subframe renderer
   // identified by |instance|.
   void SetPageFocus(SiteInstance* instance, bool is_focused);
@@ skipping 44 matching lines @@
 
   // Overall load progress.
   double load_progress_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameTree);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_FRAME_TREE_H_