cc: Add UMA stats for record and raster time.

cc/resources/display_list_recording_source.cc

Index: cc/resources/display_list_recording_source.cc
diff --git a/cc/resources/display_list_recording_source.cc b/cc/resources/display_list_recording_source.cc
index 3a47c9067ca4dc7e0634aca8269100887a91a304..7ada580ab931d70f4e1ff5dcdbc2579d02e5a353 100644
--- a/cc/resources/display_list_recording_source.cc
+++ b/cc/resources/display_list_recording_source.cc
@@ -6,6 +6,7 @@
 
 #include <algorithm>
 
+#include "cc/base/histograms.h"
 #include "cc/base/region.h"
 #include "cc/layers/content_layer_client.h"
 #include "cc/resources/display_item_list.h"
@@ -22,6 +23,11 @@ const int kPixelDistanceToRecord = 8000;
 // operations.
 const int kOpCountThatIsOkToAnalyze = 10;
 
+DEFINE_SCOPED_UMA_HISTOGRAM_AREA_TIMER(
+    ScopedDisplayListRecordingSourceUpdateTimer,
+    "Compositing.DisplayListRecordingSource.UpdateUs",
+    "Compositing.DisplayListRecordingSource.UpdateInvalidatedAreaPerMs");
+
 }  // namespace
 
 namespace cc {
@@ -49,6 +55,7 @@ bool DisplayListRecordingSource::UpdateAndExpandInvalidation(
     const gfx::Rect& visible_layer_rect,
     int frame_number,
     RecordingMode recording_mode) {
+  ScopedDisplayListRecordingSourceUpdateTimer timer;
   bool updated = false;
 
   if (size_ != layer_size) {
@@ -74,6 +81,12 @@ bool DisplayListRecordingSource::UpdateAndExpandInvalidation(
     updated = true;
   }
 
+  // Count the area that is being invalidated.
+  Region recorded_invalidation(*invalidation);
+  recorded_invalidation.Intersect(recorded_viewport_);
+  for (Region::Iterator it(recorded_invalidation); it.has_rect(); it.next())
+    timer.AddArea(it.rect().size().GetArea());
+
   if (!updated && !invalidation->Intersects(recorded_viewport_))
     return false;