[Android] Support startup histogram.

chrome/app/android/chrome_main_delegate_android.cc

Index: chrome/app/android/chrome_main_delegate_android.cc
diff --git a/chrome/app/android/chrome_main_delegate_android.cc b/chrome/app/android/chrome_main_delegate_android.cc
index 6b726c6147f63599fa024b026a7a59b86540dd56..2b62047c837bce8a3540d57e3ce34fa9d4035967 100644
--- a/chrome/app/android/chrome_main_delegate_android.cc
+++ b/chrome/app/android/chrome_main_delegate_android.cc
@@ -8,6 +8,8 @@
 #include "base/debug/trace_event.h"
 #include "chrome/browser/android/chrome_jni_registrar.h"
 #include "chrome/browser/android/chrome_startup_flags.h"
+#include "chrome/browser/android/uma_utils.h"
+#include "chrome/common/startup_metric_utils.h"
 #include "content/public/browser/browser_main_runner.h"
 
 // ChromeMainDelegateAndroid is created when the library is loaded. It is always
@@ -33,10 +35,14 @@ int ChromeMainDelegateAndroid::RunProcess(
     RegisterApplicationNativeMethods(env);
 
     // Because the browser process can be started asynchronously as a series of
-    // of UI thread tasks a second request to start it can come in while the
-    // first request is still being processed. We must keep the same
+    // UI thread tasks a second request to start it can come in while the
+    // first request is still being processed. Chrome must keep the same
     // browser runner for the second request.
+    // Also only record the start time the first time round, since this is the
+    // start time of the application, and will be same for all requests.
     if (!browser_runner_.get()) {
+      base::Time startTime = chrome::android::GetMainEntryPointTime();
+      startup_metric_utils::RecordSavedMainEntryPointTime(startTime);
       browser_runner_.reset(content::BrowserMainRunner::Create());
     }
     return browser_runner_->Initialize(main_function_params);