cc: Add LayerTreeSetting to disable cached picture raster.

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 <stddef.h>
 
+#include "base/command_line.h"
+#include "cc/base/switches.h"
 #include "cc/layers/picture_image_layer_impl.h"
 #include "cc/playback/display_item_list_settings.h"
 #include "cc/playback/drawing_display_item.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkImage.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
 #include "ui/gfx/skia_util.h"
 
 namespace cc {
 
+namespace {
+
+static bool UseCachedPictureRaster() {

[vmpstr, 2016/03/25 21:45:12]

Is it possible to plumb this through layer tree settings? I don't really want to
set the precedent of checking the command line in our layers... The
web_content_layer_impl is kind of the blink interface, so I'm not sure if they
can access layer tree settings.

[Khushal, 2016/03/25 21:53:48]

Sure I can add a LayerTreeSetting for this. Yup, cc/blink wouldn't have any
access to it, so we would have to use the command line flag there.

+  static bool use = !base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kDisableCachedPictureRaster);
+  return use;
+}
+}
+
 scoped_refptr<PictureImageLayer> PictureImageLayer::Create() {
   return make_scoped_refptr(new PictureImageLayer());
 }
 
 PictureImageLayer::PictureImageLayer() : PictureLayer(this) {}
 
 PictureImageLayer::~PictureImageLayer() {
   ClearClient();
 }
 
@@ skipping 22 matching lines @@
 gfx::Rect PictureImageLayer::PaintableRegion() {
   return gfx::Rect(bounds());
 }
 
 scoped_refptr<DisplayItemList> PictureImageLayer::PaintContentsToDisplayList(
     ContentLayerClient::PaintingControlSetting painting_control) {
   DCHECK(image_);
   DCHECK_GT(image_->width(), 0);
   DCHECK_GT(image_->height(), 0);
 
-  // Picture image layers can be used with GatherPixelRefs, so cached SkPictures
-  // are currently required.
   DisplayItemListSettings settings;
-  settings.use_cached_picture = true;
+  settings.use_cached_picture = UseCachedPictureRaster();
   scoped_refptr<DisplayItemList> display_list =
       DisplayItemList::Create(PaintableRegion(), settings);
 
   SkPictureRecorder recorder;
   SkCanvas* canvas =
       recorder.beginRecording(gfx::RectToSkRect(PaintableRegion()));
 
   SkScalar content_to_layer_scale_x =
       SkFloatToScalar(static_cast<float>(bounds().width()) / image_->width());
   SkScalar content_to_layer_scale_y =
@@ skipping 14 matching lines @@
 
 bool PictureImageLayer::FillsBoundsCompletely() const {
   return false;
 }
 
 size_t PictureImageLayer::GetApproximateUnsharedMemoryUsage() const {
   return 0;
 }
 
 }  // namespace cc