Hack SkRecord in as an alternate recording mode in cc/resources/picture.

cc/resources/picture.cc

Index: cc/resources/picture.cc
diff --git a/cc/resources/picture.cc b/cc/resources/picture.cc
index 48f03e0ba842a864975eef07cb8e19cf2988db4f..a95cdaa9ad3770b1f4f619f18066447bf8312013 100644
--- a/cc/resources/picture.cc
+++ b/cc/resources/picture.cc
@@ -192,6 +192,11 @@ Picture::~Picture() {
 }
 
 Picture* Picture::GetCloneForDrawingOnThread(unsigned thread_index) {
+  // We don't need clones to draw from multiple threads with SkRecord.
+  if (playback_) {
+    return this;
+  }
+
   // SkPicture is not thread-safe to rasterize with, this returns a clone
   // to rasterize with on a specific thread.
   CHECK_GE(clones_.size(), thread_index);
@@ -214,6 +219,11 @@ bool Picture::IsSuitableForGpuRasterization() const {
 void Picture::CloneForDrawing(int num_threads) {
   TRACE_EVENT1("cc", "Picture::CloneForDrawing", "num_threads", num_threads);
 
+  // We don't need clones to draw from multiple threads with SkRecord.
+  if (playback_) {
+    return;
+  }
+
   DCHECK(picture_);
   DCHECK(clones_.empty());
 
@@ -254,6 +264,8 @@ void Picture::Record(ContentLayerClient* painter,
   SkTileGridFactory factory(tile_grid_info);
   SkPictureRecorder recorder;
 
+  scoped_ptr<EXPERIMENTAL::SkRecording> recording;
+
   skia::RefPtr<SkCanvas> canvas;
   canvas = skia::SharePtr(
       recorder.beginRecording(layer_rect_.width(),
@@ -273,6 +285,11 @@ void Picture::Record(ContentLayerClient* painter,
       // canvas.
       canvas.clear();
       break;
+    case RECORD_WITH_SKRECORD:
+      recording.reset(new EXPERIMENTAL::SkRecording(layer_rect_.width(),
+                                                    layer_rect_.height()));
+      canvas = skia::SharePtr(recording->canvas());
+      break;
     default:
       NOTREACHED();
   }
@@ -297,6 +314,11 @@ void Picture::Record(ContentLayerClient* painter,
   picture_ = skia::AdoptRef(recorder.endRecording());
   DCHECK(picture_);
 
+  if (recording) {
+    canvas.clear();  // Drop ref on canvas before calling releasePlayback().

[enne (OOO), 2014/04/25 17:34:22]

Can this comment say why and not what?

Alternatively, don't clear the canvas and just leave a comment that says "After
releasing the SkPlayback, the canvas is no longer valid?".  It doesn't get used
here in this function and would blow up immediately if it did post-release.

[mtklein, 2014/04/28 19:03:18]

Done.

+    playback_.reset(recording->releasePlayback());
+  }
+
   opaque_rect_ = gfx::ToEnclosedRect(opaque_layer_rect);
 
   EmitTraceSnapshot();
@@ -379,7 +401,11 @@ int Picture::Raster(
 
   canvas->scale(contents_scale, contents_scale);
   canvas->translate(layer_rect_.x(), layer_rect_.y());
-  picture_->draw(canvas, callback);
+  if (playback_) {
+    playback_->draw(canvas);
+  } else {
+    picture_->draw(canvas, callback);
+  }
   SkIRect bounds;
   canvas->getClipDeviceBounds(&bounds);
   canvas->restore();
@@ -394,7 +420,11 @@ void Picture::Replay(SkCanvas* canvas) {
   TRACE_EVENT_BEGIN0("cc", "Picture::Replay");
   DCHECK(picture_);
 
-  picture_->draw(canvas);
+  if (playback_) {
+    playback_->draw(canvas);
+  } else {
+    picture_->draw(canvas);
+  }
   SkIRect bounds;
   canvas->getClipDeviceBounds(&bounds);
   TRACE_EVENT_END1("cc", "Picture::Replay",