Adding histograms showing fraction of page load times

chrome/browser/net/cache_stats.h

Index: chrome/browser/net/cache_stats.h
===================================================================
--- chrome/browser/net/cache_stats.h	(revision 0)
+++ chrome/browser/net/cache_stats.h	(revision 0)
@@ -0,0 +1,104 @@
+// 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_NET_CACHE_STATS_H_
+#define CHROME_BROWSER_NET_CACHE_STATS_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/hash_tables.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "base/message_loop.h"
+#include "base/time.h"
+#include "content/public/browser/web_contents_observer.h"
+#include "net/base/network_delegate.h"
+
+class TabContents;
+
+namespace base {
+class Histogram;
+}
+
+namespace net {
+class URLRequest;
+}
+
+namespace chrome_browser_net {
+
+// This class collects UMA stats about cache performance.  It is a singleton
+// and lives on the IO thread.
+class CacheStats : public MessageLoop::DestructionObserver {
+ public:
+  enum TabEvent {
+    SPINNER_START,
+    SPINNER_STOP
+  };
+  static CacheStats* GetInstance();
+  void OnCacheWaitStateChange(const net::URLRequest& request,
+                              net::NetworkDelegate::CacheWaitState state);
+  void OnTabEvent(std::pair<int, int> render_view_id, TabEvent event);
+  virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
+  virtual ~CacheStats();
+
+ private:
+  friend struct DefaultSingletonTraits<CacheStats>;
+  struct TabLoadStats;
+  typedef std::map<std::pair<int, int>, TabLoadStats*> TabLoadStatsMap;
+
+  CacheStats();
+  // Gets TabLoadStats for a given render view.
+  TabLoadStats* GetTabLoadStats(std::pair<int, int> render_view_id);
+  // Deletes TabLoadStats no longer needed for a render view.
+  void RemoveTabLoadStats(std::pair<int, int> render_view_id);
+  // Sets a timer for a given tab to collect stats.  timer_index indicates
+  // how many times stats have been collected since the navigation has started
+  // for this tab.
+  void ScheduleTimer(TabLoadStats* stats, int timer_index);
+  // The callback when a timer fires to collect stats again.
+  void TimerCb(TabLoadStats* stats, int timer_index);
+  // Helper function to put the current set of cache statistics into an UMA
+  // histogram.
+  void RecordCacheFractionHistogram(base::TimeDelta elapsed,
+                                    base::TimeDelta cache_time,
+                                    bool is_load_done);
+
+  TabLoadStatsMap tab_load_stats_;
+  std::vector<base::Histogram*> final_histograms_;
+  std::vector<base::Histogram*> intermediate_histograms_;
+  bool registered_message_loop_destruction_observer_;
+};
+
+// A WebContentsObserver watching all tabs, notifying CacheStats
+// whenever the spinner starts or stops for a given tab, and when a renderer
+// is no longer used.
+class CacheStatsTabHelper : public content::WebContentsObserver {
+ public:
+  explicit CacheStatsTabHelper(TabContents* tab);
+  virtual ~CacheStatsTabHelper();
+  virtual void DidStartProvisionalLoadForFrame(
+      int64 frame_id,
+      bool is_main_frame,
+      const GURL& validated_url,
+      bool is_error_page,
+      content::RenderViewHost* render_view_host) OVERRIDE;
+  virtual void DidStopLoading(content::RenderViewHost* render_view_host)
+      OVERRIDE;
+
+ private:
+  // Calls into CacheStats to notify that a reportable event has occurred
+  // for the tab being observed.
+  void NotifyCacheStats(CacheStats::TabEvent event,
+                        content::RenderViewHost* render_view_host);
+
+  CacheStats* cache_stats_;
+  bool is_profile_otr_;
+};
+
+}  // namespace chrome_browser_net
+
+#endif  // CHROME_BROWSER_NET_CACHE_STATS_H_