Add histogram to track prerender sessions

chrome/browser/prerender/prerender_manager.cc

Index: chrome/browser/prerender/prerender_manager.cc
diff --git a/chrome/browser/prerender/prerender_manager.cc b/chrome/browser/prerender/prerender_manager.cc
index 1b75670a4e650aaa4bdd09210113ce75aeb16178..90ccb3735ee187d3c27c7b471c0bfc1d28f206f1 100644
--- a/chrome/browser/prerender/prerender_manager.cc
+++ b/chrome/browser/prerender/prerender_manager.cc
@@ -4,6 +4,7 @@
 
 #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"
@@ -11,8 +12,17 @@
 #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_;