Prerender: Remove PerceivedPLT histograms

chrome/browser/prerender/prerender_tab_helper.h

 // Copyright (c) 2012 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 CHROME_BROWSER_PRERENDER_PRERENDER_TAB_HELPER_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_TAB_HELPER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "chrome/browser/prerender/prerender_histograms.h"
 #include "chrome/browser/prerender/prerender_origin.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "url/gurl.h"
 
 namespace prerender {
 
 class PrerenderManager;
 
-// PrerenderTabHelper is responsible for recording perceived pageload times
-// to compare PLT's with prerendering enabled and disabled.
+// Notifies the PrerenderManager with the events happening in the prerendered
+// WebContents.
 class PrerenderTabHelper
     : public content::WebContentsObserver,
       public content::WebContentsUserData<PrerenderTabHelper> {
  public:
   ~PrerenderTabHelper() override;
 
   // content::WebContentsObserver implementation.
   void DidGetRedirectForResourceRequest(
       const content::ResourceRedirectDetails& details) override;
-  void DidStopLoading() override;
   void DidStartNavigation(
       content::NavigationHandle* navigation_handle) override;
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override;
 
   // Called when the URL of the main frame changed, either when the load
   // commits, or a redirect happens.
   void MainFrameUrlDidChange(const GURL& url);
 
   // Called when this prerendered WebContents has just been swapped in.
   void PrerenderSwappedIn();
 
   base::TimeTicks swap_ticks() const { return swap_ticks_; }
 
   Origin origin() const { return origin_; }
 
  private:
   explicit PrerenderTabHelper(content::WebContents* web_contents);
   friend class content::WebContentsUserData<PrerenderTabHelper>;
 
-  void RecordPerceivedPageLoadTime(
-      base::TimeDelta perceived_page_load_time,
-      double fraction_plt_elapsed_at_swap_in);
-
   // Retrieves the PrerenderManager, or NULL, if none was found.
   PrerenderManager* MaybeGetPrerenderManager() const;
 
   // Returns the current TimeTicks synchronized with PrerenderManager ticks. In
   // tests the clock can be mocked out in PrerenderManager, but in production
   // this should be always TimeTicks::Now().
   base::TimeTicks GetTimeTicksFromPrerenderManager() const;
 
   // Returns whether the WebContents being observed is currently prerendering.
   bool IsPrerendering();
 
-  // The type the current pending navigation, if there is one. If the tab is a
-  // prerender before swap, the value is always NAVIGATION_TYPE_PRERENDERED,
-  // even if the prerender is not currently loading.
-  NavigationType navigation_type_;
-
-  // If |navigation_type_| is not NAVIGATION_TYPE_NORMAL, the origin of the
-  // relevant prerender. Otherwise, ORIGIN_NONE.
+  // The origin of the relevant prerender or ORIGIN_NONE if there is no
+  // prerender associated with the WebContents.
   Origin origin_;
 
-  // System time at which the current load was started for the purpose of
-  // the perceived page load time (PPLT). If null, there is no current
-  // load.
-  base::TimeTicks pplt_load_start_;
-
-  // System time at which the actual pageload started (pre-swapin), if
-  // a applicable (in cases when a prerender that was still loading was
-  // swapped in).
-  base::TimeTicks actual_load_start_;
-
-  // Record the most recent swap time. This differs from |pplt_load_start_| in
-  // that it is not reset in various circumstances, like a load being stopped.
+  // Record the most recent swap time.
   base::TimeTicks swap_ticks_;
 
   // Current URL being loaded.
   GURL url_;
 
   base::WeakPtrFactory<PrerenderTabHelper> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderTabHelper);
 };
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_TAB_HELPER_H_