Add Histograms to Measure Time in BrowserMainRunnerImpl::Initialize

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index afd93fb6f832f9186c35e3cfdb7f17cf953edf8b..943188a424f38c37175063f1a23984dde55595fa 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -44920,6 +44920,32 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Startup.BrowserMainRunnerImplInitializeLongTime"
+    units="milliseconds">
+  <owner>robliao@chromium.org</owner>
+  <summary>
+    The amount of time that elapsed during BrowserMainRunnerImpl::Initialize.
+  </summary>
+</histogram>
+
+<histogram name="Startup.BrowserMainRunnerImplInitializeStep1Time"
+    units="milliseconds">
+  <owner>robliao@chromium.org</owner>
+  <summary>
+    The amount of time that elapsed during the first section of
+    BrowserMainRunnerImpl::Initialize.
+  </summary>
+</histogram>
+
+<histogram name="Startup.BrowserMainRunnerImplInitializeStep2Time"
+    units="milliseconds">
+  <owner>robliao@chromium.org</owner>
+  <summary>
+    The amount of time that elapsed during the second section of
+    BrowserMainRunnerImpl::Initialize.
+  </summary>
+</histogram>
+
 <histogram name="Startup.BrowserMessageLoopStartHardFaultCount" units="faults">
   <owner>chrisha@chromium.org</owner>
   <summary>