Add histogram to track prerender sessions

chrome/browser/prerender/prerender_manager.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_manager.h"
 
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/renderer_host/render_view_host.h"
 #include "chrome/browser/tab_contents/tab_contents.h"
 #include "chrome/browser/tab_contents/render_view_host_manager.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/render_messages.h"
 
+// static
+PrerenderManager::SessionType PrerenderManager::GetSessionType() {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnablePagePrerender))

[jar (doing other things), 2011/01/26 21:31:32]

nit: (I think) indent only 4 spaces from previous line.

[gavinp, 2011/01/27 04:29:29]

jar & I followed up on this: brettw said that indent by 8 here is acceptable, as
is indent by four based on readability.  However, this is informational only, as
this function doesn't exist in the new upload.

+    return PRERENDERING_ON;
+  return PRERENDERING_OFF;
+}
+
 struct PrerenderManager::PrerenderContentsData {
   PrerenderContents* contents_;
   base::Time start_time_;
   GURL url_;
   PrerenderContentsData(PrerenderContents* contents,
                         base::Time start_time,
                         GURL url)
       : contents_(contents),
         start_time_(start_time),
         url_(url) {
@@ skipping 106 matching lines @@
 bool PrerenderManager::IsPrerenderElementFresh(const base::Time start) const {
   base::Time now = GetCurrentTime();
   return (now - start < max_prerender_age_);
 }
 
 PrerenderContents* PrerenderManager::CreatePrerenderContents(
     const GURL& url,
     const std::vector<GURL>& alias_urls) {
   return new PrerenderContents(this, profile_, url, alias_urls);
 }