Remove the unmaintained performance monitor.

chrome/browser/chrome_browser_main.h

Index: chrome/browser/chrome_browser_main.h
diff --git a/chrome/browser/chrome_browser_main.h b/chrome/browser/chrome_browser_main.h
index 21138a06cf11dc25ed0cc4a979f255af55c4127a..e62f0effca7ba136097fb9289b425ee0e9b7efee 100644
--- a/chrome/browser/chrome_browser_main.h
+++ b/chrome/browser/chrome_browser_main.h
@@ -45,10 +45,6 @@ namespace chrome_browser_metrics {
 class TrackingSynchronizer;
 }
 
-namespace performance_monitor {
-class StartupTimer;
-}
-
 class ChromeBrowserMainParts : public content::BrowserMainParts {
  public:
   virtual ~ChromeBrowserMainParts();
@@ -135,11 +131,6 @@ class ChromeBrowserMainParts : public content::BrowserMainParts {
   // it is destroyed last.
   scoped_ptr<ShutdownWatcherHelper> shutdown_watcher_;
 
-  // A timer to hold data regarding startup and session restore times for
-  // PerformanceMonitor so that we don't have to start the entire
-  // PerformanceMonitor at browser startup.
-  scoped_ptr<performance_monitor::StartupTimer> startup_timer_;
-
   // Creating this object starts tracking the creation and deletion of Task
   // instance. This MUST be done before main_message_loop, so that it is
   // destroyed after the main_message_loop.