Paint Profiler: unroll SkPictures

Source/platform/graphics/InterceptingCanvas.cpp

+// Copyright 2015 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 "config.h"
+#include "platform/graphics/InterceptingCanvas.h"
+
+namespace blink {
+
+void InterceptingCanvasBase::unrollDrawPicture(const SkPicture* picture, const SkMatrix* matrix, const SkPaint* paint, SkPicture::AbortCallback* abortCallback)
+{
+    int saveCount = this->getSaveCount();
+    if (paint) {
+        SkRect newBounds = picture->cullRect();

[f(malita), 2015/06/17 18:20:56]

Nit: the 'bounds' saveLayer arg is optional, so I think it would be OK to skip
this computation and just pass NULL instead.

[caseq, 2015/06/17 18:29:47]

Would it be the same performance-wise? I was thinking that perhaps for drawing a
small picture on a large bitmap-backed canvas this might matter, and since this
also runs in profiler, I thought we better follow what Skia would do.

[f(malita), 2015/06/17 18:41:56]

It defaults to using the current clip bounds, but if the clip is not tight then
this can potentially be (a lot) more expensive.

I hadn't realized this is contributing to the profiler times, so yeah, it makes
sense to use the picture cull rect for perf reasons - ignore my nit :)

+        if (matrix)
+            matrix->mapRect(&newBounds);
+        this->saveLayer(&newBounds, paint);
+    } else if (matrix) {
+        this->save();
+    }
+    if (matrix)
+        this->concat(*matrix);
+
+    picture->playback(this, abortCallback);
+
+    this->restoreToCount(saveCount);
+}
+
+} // namespace blink