Create a mapper to compute browser and renderer startup durations.

tracing/tracing/extras/chrome/chrome_browser_helper.html

Index: tracing/tracing/extras/chrome/chrome_browser_helper.html
diff --git a/tracing/tracing/extras/chrome/chrome_browser_helper.html b/tracing/tracing/extras/chrome/chrome_browser_helper.html
index 46b00bd5c9189e959a57a7a859a8f323d4b9407c..b7ee72c1b0dfdc4775022c9e509f56d93ab57172 100644
--- a/tracing/tracing/extras/chrome/chrome_browser_helper.html
+++ b/tracing/tracing/extras/chrome/chrome_browser_helper.html
@@ -20,9 +20,11 @@ tr.exportTo('tr.e.audits', function() {
   }
 
   ChromeBrowserHelper.isBrowserProcess = function(process) {
-    if (!process.findAtMostOneThreadNamed('CrBrowserMain'))
-      return false;
-    return true;
+    return !!process.findAtMostOneThreadNamed('CrBrowserMain');
+  };
+
+  ChromeBrowserHelper.isRendererProcess = function(process) {

[nduca, 2015/08/14 22:28:49]

you'll have to use ChromeRendererHelper for this. Its not actually as easy as
you think and we need the logic centralized [content shell etc have various non
trivial tricks that cause things to get named whackily]

[beaudoin, 2015/08/18 16:16:54]

Done.

+    return !!process.findAtMostOneThreadNamed('CrRendererMain');
   };
 
   ChromeBrowserHelper.prototype = {