Back PaintRecord with PaintOpBuffer instead of SkPicture

cc/paint/paint_recorder.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/paint/paint_recorder.h"
 
+#include "cc/paint/paint_op_buffer.h"
+
 namespace cc {
 
 PaintRecorder::PaintRecorder() = default;
+
 PaintRecorder::~PaintRecorder() = default;
 
+PaintCanvas* PaintRecorder::beginRecording(const SkRect& bounds) {
+  buffer_.reset(new PaintOpBuffer(bounds));
+  canvas_.emplace(buffer_.get());
+  return getRecordingCanvas();
+}
+
+sk_sp<PaintRecord> PaintRecorder::finishRecordingAsPicture() {
+  // SkPictureRecorder users expect that their saves are automatically
+  // closed for them.
+  //
+  // NOTE: Blink paint in general doesn't appear to need this, but the
+  // RecordingImageBufferSurface::fallBackToRasterCanvas finishing off the
+  // current frame depends on this.  Maybe we could remove this assumption and
+  // just have callers do it.
+  canvas_->restoreToCount(1);
+
+  // Some users (e.g. printing) use the existence of the recording canvas
+  // to know if recording is finished, so reset it here.
+  canvas_.reset();
+
+  buffer_->ShrinkToFit();
+  return std::move(buffer_);
+}
+
 }  // namespace cc