cc: Add UMA stats for record and raster time.

cc/layers/picture_layer.cc

Index: cc/layers/picture_layer.cc
diff --git a/cc/layers/picture_layer.cc b/cc/layers/picture_layer.cc
index 5c4cb068d14dda4ac3ea57e789f21097dc0755f1..a4108f29a1105a6e44b065233450b580b98f7939 100644
--- a/cc/layers/picture_layer.cc
+++ b/cc/layers/picture_layer.cc
@@ -5,6 +5,8 @@
 #include "cc/layers/picture_layer.h"
 
 #include "base/auto_reset.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/timer/elapsed_timer.h"
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/picture_layer_impl.h"
 #include "cc/resources/display_list_recording_source.h"
@@ -136,6 +138,7 @@ bool PictureLayer::Update(ResourceUpdateQueue* queue,
                layer_tree_host()->source_frame_number());
   devtools_instrumentation::ScopedLayerTreeTask update_layer(
       devtools_instrumentation::kUpdateLayer, id(), layer_tree_host()->id());
+  base::ElapsedTimer timer;
 
   // Calling paint in WebKit can sometimes cause invalidations, so save
   // off the invalidation prior to calling update.
@@ -152,10 +155,12 @@ bool PictureLayer::Update(ResourceUpdateQueue* queue,
   // anything not explicitly recorded in this frame. We give this region
   // to the impl side so that it drops tiles that may not have a recording
   // for them.
+  int recorded_area = 0;
   DCHECK(client_);
   updated |= recording_source_->UpdateAndExpandInvalidation(
       client_, &recording_invalidation_, layer_size, visible_layer_rect,
-      update_source_frame_number_, RecordingSource::RECORD_NORMALLY);
+      update_source_frame_number_, RecordingSource::RECORD_NORMALLY,
+      &recorded_area);

[enne (OOO), 2015/04/09 17:37:34]

Yeah, I think this is the right metric.  Can you put all of this internal to
PicturePile so recorded area doesn't have to get returned?

Yeah, yeah, you have to duplicate the UMA stat call, but I think it's ok to have
bolted on stats, rather than plumbing their dependencies through like they're
first class citizens.

[jbroman, 2015/04/09 20:54:06]

Okay, split (with different stat names). This triggered Fowler's rule of three,
so I refactored into a macro (but the chromium-style plugin made me make the
destructor non-inline because it has a templated member . . . oh well). PTAL.

   last_updated_visible_content_rect_ = visible_content_rect();
 
   if (updated) {
@@ -166,6 +171,12 @@ bool PictureLayer::Update(ResourceUpdateQueue* queue,
     recording_invalidation_.Clear();
   }
 
+  base::TimeDelta elapsed = timer.Elapsed();
+  UMA_HISTOGRAM_COUNTS("Renderer4.PictureLayerUpdateUs",
+                       elapsed.InMicroseconds());
+  UMA_HISTOGRAM_COUNTS("Renderer4.PictureLayerUpdatePixelsPerMs",
+                       recorded_area / elapsed.InMillisecondsF());
+
   return updated;
 }
 
@@ -190,7 +201,7 @@ skia::RefPtr<SkPicture> PictureLayer::GetPicture() const {
     Region recording_invalidation;
     recording_source->UpdateAndExpandInvalidation(
         client_, &recording_invalidation, layer_size, gfx::Rect(layer_size),
-        update_source_frame_number_, RecordingSource::RECORD_NORMALLY);
+        update_source_frame_number_, RecordingSource::RECORD_NORMALLY, nullptr);
 
     scoped_refptr<RasterSource> raster_source =
         recording_source->CreateRasterSource(false);