Add Perceived PageLoad Time (PPLT) metrics for Prerender Experiments,...

chrome/browser/prerender/prerender_plt_recorder.cc

+// Copyright (c) 2010 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.
+
+#include "chrome/browser/prerender/prerender_plt_recorder.h"
+
+#include "base/time.h"
+#include "chrome/browser/prerender/prerender_manager.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/tab_contents/tab_contents.h"
+#include "chrome/common/render_messages.h"
+
+PrerenderPLTRecorder::PrerenderPLTRecorder(TabContents* tab_contents)
+    : tab_contents_(tab_contents),
+      pplt_load_start_() {
+
+}
+
+PrerenderPLTRecorder::~PrerenderPLTRecorder() {
+}
+
+bool PrerenderPLTRecorder::OnMessageReceived(const IPC::Message& message) {
+  IPC_BEGIN_MESSAGE_MAP(PrerenderPLTRecorder, message)
+      IPC_MESSAGE_HANDLER(ViewHostMsg_DidStartProvisionalLoadForFrame,
+                          OnDidStartProvisionalLoadForFrame)
+  IPC_END_MESSAGE_MAP()
+  return false;
+}
+
+void PrerenderPLTRecorder::OnDidStartProvisionalLoadForFrame(int64 frame_id,
+                                                    bool is_main_frame,

[brettw, 2011/01/26 22:13:28]

Since these won't fit, all the arguments should just be indented 4 spaces (frame
ID should be moved down to the next line).

+                                                    const GURL& url) {
+  if (is_main_frame) {
+    // Record the beginning of a new PPLT navigation.
+    pplt_load_start_ = base::TimeTicks::Now();
+  }
+}
+
+void PrerenderPLTRecorder::DidStopLoading() {
+  // Compute the PPLT metric and report it in a histogram, if needed.
+  PrerenderManager* pm = tab_contents_->profile()->GetPrerenderManager();
+  if (pm != NULL && !pplt_load_start_.is_null())
+    pm->RecordPerceivedPageLoadTime(base::TimeTicks::Now() - pplt_load_start_);
+
+  // Reset the PPLT metric.
+  pplt_load_start_ = base::TimeTicks();
+}