PerformanceMonitor: UMA alert for high browser CPU usage.

chrome/browser/chrome_browser_main.cc

Index: chrome/browser/chrome_browser_main.cc
diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index fbbff83d72d2001e69c48ecff27f601ecf7a82f6..6dbc1a67481994d810a1f11c713b5f8ffb5b50ac 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -1621,10 +1621,7 @@ bool ChromeBrowserMainParts::MainMessageLoopRun(int* result_code) {
   base::RunLoop run_loop;
 #endif
 
-  if (CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kPerformanceMonitorGathering)) {
-    performance_monitor::PerformanceMonitor::GetInstance()->Start();
-  }
+  performance_monitor::PerformanceMonitor::GetInstance()->Start();

[Devlin, 2013/09/13 18:14:09]

(One of) the reason(s) we never turned this on by default was because we weren't
entirely sure how much of a performance impact it would have (and it would be
terrible if we reduced performance significantly while watching for
significantly-reduced performance).  I just want to make sure that this has been
checked, and everyone is okay with the potential overhead.

[oystein (OOO til 10th of July), 2013/09/13 20:41:55]

That's why all of the DB stuff is disabled by default still; the only impact on
the UI thread now is the initial task creation and then enumerating the render
hosts every 10 seconds.

 
   run_loop.Run();