cc: Add UMA stats for record and raster time.

cc/resources/picture_pile.cc

Index: cc/resources/picture_pile.cc
diff --git a/cc/resources/picture_pile.cc b/cc/resources/picture_pile.cc
index 2ce3e500f2ea86458054ed71b8854a096fff5328..16167f4cf50861523632688cb975d5e26ade0aa0 100644
--- a/cc/resources/picture_pile.cc
+++ b/cc/resources/picture_pile.cc
@@ -8,6 +8,7 @@
 #include <limits>
 #include <vector>
 
+#include "cc/base/histograms.h"
 #include "cc/base/region.h"
 #include "cc/resources/picture_pile_impl.h"
 #include "skia/ext/analysis_canvas.h"
@@ -149,6 +150,11 @@ const bool kDefaultClearCanvasSetting = false;
 const bool kDefaultClearCanvasSetting = true;
 #endif
 
+DEFINE_SCOPED_UMA_HISTOGRAM_AREA_TIMER(
+    ScopedPicturePileUpdateTimer,
+    "Renderer4.PicturePileRecordUs",
+    "Renderer4.PicturePileRecordedAreaPerMs");
+
 }  // namespace
 
 namespace cc {
@@ -181,6 +187,8 @@ bool PicturePile::UpdateAndExpandInvalidation(
     const gfx::Rect& visible_layer_rect,
     int frame_number,
     RecordingSource::RecordingMode recording_mode) {
+  ScopedPicturePileUpdateTimer timer;
+
   gfx::Rect interest_rect = visible_layer_rect;
   interest_rect.Inset(-pixel_record_distance_, -pixel_record_distance_);
   recorded_viewport_ = interest_rect;
@@ -188,6 +196,11 @@ bool PicturePile::UpdateAndExpandInvalidation(
 
   bool updated = ApplyInvalidationAndResize(interest_rect, invalidation,
                                             layer_size, frame_number);
+
+  // Count the area that is being invalidated.
+  for (Region::Iterator it(*invalidation); it.has_rect(); it.next())

[enne (OOO), 2015/04/13 21:52:27]

You need to intersect these invalidations with the interest rect.  Both
recording sources would handle a billion pixel long page that fully invalidated
every frame at the same speed as an interest rect-sized page that fully
invalidated every frame.

[jbroman, 2015/04/14 16:02:17]

Which rect is the right one to intersect with? I see interest_rect in
PicturePile, but not in DisplayListRecordingSource, and it's not clear to me
what the distinction between the interest rect and the recorded viewport
(apparently the intsersection of the interest rect with the layer bounds?) is.

Can you clarify this for me, please? Thanks for your patience. :)

[enne (OOO), 2015/04/14 16:55:19]

Oops, sorry forgot to address this comment.  You should intersect with the
recorded_viewport_, which is the interest rect intersected the layer bounds.

+    timer.AddArea(it.rect().size().GetArea());
+
   std::vector<gfx::Rect> invalid_tiles;
   GetInvalidTileRects(interest_rect, &invalid_tiles);
   std::vector<gfx::Rect> record_rects;