Correctly record and pass around navigation start time.

components/web_view/navigation_entry.h

 // Copyright 2015 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 COMPONENTS_WEB_VIEW_NAVIGATION_ENTRY_H_
 #define COMPONENTS_WEB_VIEW_NAVIGATION_ENTRY_H_
 
 #include "components/web_view/url_request_cloneable.h"
 
 #include "url/gurl.h"
 
 namespace web_view {
 
 // Contains all information needed about an individual navigation in the
 // navigation stack.
 class NavigationEntry {
  public:
   explicit NavigationEntry(mojo::URLRequestPtr original_request);
   explicit NavigationEntry(const GURL& raw_url);
   ~NavigationEntry();
 
   // Builds a copy of the URLRequest that generated this navigation. This
   // method is heavyweight as it clones a few mojo pipes.
-  mojo::URLRequestPtr BuildURLRequest() const;
+  mojo::URLRequestPtr BuildURLRequest();
 
  private:
   // TODO(erg): This is not enough information to regenerate the state of the
   // world. This is only enough information to regenerate some top level frame
   // navigations. A full implementation would require individual
   // FrameNavigationEntry objects like in content::NavigationEntryImpl.
   URLRequestCloneable url_request_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationEntry);
 };
 
 }  // namespace web_view
 
 #endif  // COMPONENTS_WEB_VIEW_NAVIGATION_ENTRY_H_