Add page load metrics for no-store forward back navigations.

content/public/browser/navigation_handle.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 CONTENT_PUBLIC_BROWSER_NAVIGATION_HANDLE_H_
 #define CONTENT_PUBLIC_BROWSER_NAVIGATION_HANDLE_H_
 
 #include <memory>
 
 #include "content/common/content_export.h"
 #include "content/public/browser/navigation_throttle.h"
 #include "content/public/common/referrer.h"
 #include "net/base/net_errors.h"
 #include "ui/base/page_transition_types.h"
 
 class GURL;
 
+namespace net {
+class HttpResponseHeaders;
+}  // namespace net
+
 namespace content {
 class NavigationData;
 class NavigationThrottle;
 class RenderFrameHost;
 class WebContents;
 
 // A NavigationHandle tracks information related to a single navigation.
 // NavigationHandles are provided to several WebContentsObserver methods to
 // allow observers to track specific navigations. Observers should clear any
 // references to a NavigationHandle at the time of
@@ skipping 115 matching lines @@
 
   // Whether the navigation has committed. This returns true for either
   // successful commits or error pages that replace the previous page
   // (distinguished by |IsErrorPage|), and false for errors that leave the user
   // on the previous page.
   virtual bool HasCommitted() = 0;
 
   // Whether the navigation resulted in an error page.
   virtual bool IsErrorPage() = 0;
 
+  // Returns the response headers for the request or nullptr if there are none.
+  // This should only be accessed after a redirect was encountered or after the
+  // navigation is ready to commit. The headers returned should not be modified,
+  // as modifications will not be reflected in the network stack.
+  virtual const net::HttpResponseHeaders* GetResponseHeaders() = 0;
+
   // Resumes a navigation that was previously deferred by a NavigationThrottle.
   virtual void Resume() = 0;
 
   // Cancels a navigation that was previously deferred by a NavigationThrottle.
   // |result| should be equal to NavigationThrottle::CANCEL or
   // NavigationThrottle::CANCEL_AND_IGNORE.
   virtual void CancelDeferredNavigation(
       NavigationThrottle::ThrottleCheckResult result) = 0;
 
   // Testing methods ----------------------------------------------------------
@@ skipping 35 matching lines @@
 
   // The NavigationData that the embedder returned from
   // ResourceDispatcherHostDelegate::GetNavigationData during commit. This will
   // be a clone of the NavigationData.
   virtual NavigationData* GetNavigationData() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_NAVIGATION_HANDLE_H_