Enable disabling WebCore::GraphicsContext in telemetry.

cc/layers/picture_image_layer.cc

 // Copyright 2010 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/layers/picture_image_layer.h"
 
 #include "cc/layers/picture_image_layer_impl.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
 namespace cc {
@@ skipping 22 matching lines @@
   // style change that affects the layer even if that change doesn't
   // affect the actual contents of the image (e.g. a CSS animation).
   // With this check in place we avoid unecessary texture uploads.
   if (bitmap.pixelRef() && bitmap.pixelRef() == bitmap_.pixelRef())
     return;
 
   bitmap_ = bitmap;
   SetNeedsDisplay();
 }
 
-void PictureImageLayer::PaintContents(SkCanvas* canvas,
-                                      const gfx::Rect& clip,
-                                      gfx::RectF* opaque) {
-  if (!canvas || !bitmap_.width() || !bitmap_.height())
+void PictureImageLayer::PaintContents(
+    SkCanvas* canvas,
+    const gfx::Rect& clip,
+    gfx::RectF* opaque,
+    ContentLayerClient::GraphicsContextStatus) {
+  if (!bitmap_.width() || !bitmap_.height())

[danakj, 2014/05/01 17:07:11]

Do you want to early out here based on the GraphicsContextStatus instead of the
null canvas? Or is removing the early out intentional?

[Stephen Chennney, 2014/05/01 19:12:26]

Sami added the !canvas check during the previous attempt at solving this
problem. Originally, and again now, there is no way this is called with a null
canvas, and as compositor code we are not concerned with preventing drawing here
for telemetry.

Having said that, would you prefer to keep the canvas check?

[danakj, 2014/05/01 19:15:14]

No, I don't want to early out on canvas if it's never null. I just want to make
sure you want this layer to be drawing its bitmap into the canvas when
GraphicsContextDisabled.

     return;
 
   SkScalar content_to_layer_scale_x =
       SkFloatToScalar(static_cast<float>(bounds().width()) / bitmap_.width());
   SkScalar content_to_layer_scale_y =
       SkFloatToScalar(static_cast<float>(bounds().height()) / bitmap_.height());
   canvas->scale(content_to_layer_scale_x, content_to_layer_scale_y);
 
   // Because PictureImageLayer always FillsBoundsCompletely it will not clear
   // before painting on playback. As a result we must configure the paint to
   // copy over the uncleared destination, rather than blending with it.
   SkPaint paint;
   paint.setXfermodeMode(SkXfermode::kSrc_Mode);
   canvas->drawBitmap(bitmap_, 0, 0, &paint);
 }
 
 bool PictureImageLayer::FillsBoundsCompletely() const {
   // PictureImageLayer will always paint to the entire layer bounds.
   return true;
 }
 
 }  // namespace cc