Add Startup.BrowserView.FirstPaint / .CompositingEnded histograms.

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 456522f7be5e0967c3375a3b69d9d8f180430f4d..33b5e79ba8511678975b5854bcc61f1f60a56d1e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -69518,6 +69518,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Startup.BrowserWindow.FirstPaint" units="ms">
+  <owner>mblsha@yandex-team.ru</owner>
+  <summary>
+    Time from browser startup to the time the first Browser window has finished
+    painting its children.
+  </summary>
+</histogram>
+
+<histogram name="Startup.BrowserWindow.FirstPaint.CompositingEnded" units="ms">
+  <owner>mblsha@yandex-team.ru</owner>
+  <summary>
+    Time from browser startup to the time the GPU has finished compositing after
+    first Browser window has finished painting its children. At this point the
+    Browser interface is visible on screen. Measures how much time does it take
+    for GPU to actually paint the first time.
+  </summary>
+</histogram>
+
 <histogram name="Startup.BrowserWindowDisplay" units="ms">
   <owner>fdoray@chromium.org</owner>
   <summary>
@@ -126787,6 +126805,8 @@ from previous Chrome versions.
       name="Startup.BrowserMessageLoopStartTimeFromMainEntry.FirstRun2"/>
   <affected-histogram name="Startup.BrowserMessageLoopStartTimeFromMainEntry2"/>
   <affected-histogram name="Startup.BrowserOpenTabs"/>
+  <affected-histogram name="Startup.BrowserWindow.FirstPaint"/>
+  <affected-histogram name="Startup.BrowserWindow.FirstPaint.CompositingEnded"/>
   <affected-histogram name="Startup.BrowserWindowDisplay"/>
   <affected-histogram name="Startup.FirstWebContents.MainFrameLoad"/>
   <affected-histogram name="Startup.FirstWebContents.MainFrameLoad2"/>