Add UMA stats for time in paint+layout, compositing, paint invalidation and paint.

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 4cfec7ee31a33fcc5ab1289cda600e2ad6961802..5429212657aa717d6cb56c731ee02f11803d7889 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -3282,6 +3282,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Blink.Compositing.UpdateTime" units="microseconds">
+  <owner>paint-dev@chromium.org</owner>
+  <summary>
+    Time spent updating compositing in the Blink document lifecyce.
+  </summary>
+</histogram>
+
 <histogram name="Blink.DecodedImage.Orientation" enum="DecodedImageOrientation">
   <owner>rob.buis@samsung.org</owner>
   <summary>Image orientation inferred during decode.</summary>
@@ -3337,6 +3344,18 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Blink.Paint.UpdateTime" units="microseconds">
+  <owner>paint-dev@chromium.org</owner>
+  <summary>Time spent updating paint in the Blink document lifecycle.</summary>
+</histogram>
+
+<histogram name="Blink.PaintInvalidation.UpdateTime" units="microseconds">
+  <owner>paint-dev@chromium.org</owner>
+  <summary>
+    Time spent updating paint invalidation in the Blink document lifecycle.
+  </summary>
+</histogram>
+
 <histogram name="Blink.RestoredCachedStyleSheet"
     enum="RestoredCachedStyleSheet">
   <obsolete>
@@ -3364,6 +3383,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Blink.StyleAndLayout.UpdateTime" units="microseconds">
+  <owner>layout-dev@chromium.org</owner>
+  <summary>
+    Time spent updating style and layout in the Blink document lifecycle.
+  </summary>
+</histogram>
+
 <histogram name="Blink.XHR.setRequestHeader.HeaderValueCategoryInRFC7230"
     enum="XMLHttpRequestHeaderValueCategoryInRFC7230">
   <owner>hiroshige@chromium.org</owner>