cc: Add flag to disable future mask tiling.

cc/layers/picture_layer.cc

 // Copyright 2012 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_layer.h"
 
 #include "base/auto_reset.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/picture_layer_impl.h"
 #include "cc/paint/paint_record.h"
 #include "cc/playback/recording_source.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 
 namespace cc {
 
 PictureLayer::PictureLayerInputs::PictureLayerInputs() = default;
 
 PictureLayer::PictureLayerInputs::~PictureLayerInputs() = default;
 
 scoped_refptr<PictureLayer> PictureLayer::Create(ContentLayerClient* client) {
   return make_scoped_refptr(new PictureLayer(client));
 }
 
 PictureLayer::PictureLayer(ContentLayerClient* client)
     : instrumentation_object_tracker_(id()),
       update_source_frame_number_(-1),
-      mask_type_(Layer::LayerMaskType::NOT_MASK) {
+      mask_type_(LayerMaskType::NOT_MASK) {
   picture_layer_inputs_.client = client;
 }
 
 PictureLayer::PictureLayer(ContentLayerClient* client,
                            std::unique_ptr<RecordingSource> source)
     : PictureLayer(client) {
   recording_source_ = std::move(source);
 }
 
 PictureLayer::~PictureLayer() {
@@ skipping 20 matching lines @@
       recording_source_->CreateRasterSource(can_use_lcd_text);
   layer_impl->set_gpu_raster_max_texture_size(
       layer_tree_host()->device_viewport_size());
   layer_impl->UpdateRasterSource(raster_source, &last_updated_invalidation_,
                                  nullptr);
   DCHECK(last_updated_invalidation_.IsEmpty());
 }
 
 void PictureLayer::SetLayerTreeHost(LayerTreeHost* host) {
   Layer::SetLayerTreeHost(host);
+  if (host && !host->GetSettings().enable_mask_tiling &&
+      mask_type_ == LayerMaskType::MULTI_TEXTURE_MASK)
+    mask_type_ = LayerMaskType::SINGLE_TEXTURE_MASK;

[trchen, 2017/02/16 23:52:30]

nit: Move after line 77 then null-check for host can be skipped.

+
   if (!host)
     return;
 
   if (!recording_source_)
     recording_source_.reset(new RecordingSource);
   recording_source_->SetSlowdownRasterScaleFactor(
       host->GetDebugState().slow_down_raster_scale_factor);
   // If we need to enable image decode tasks, then we have to generate the
   // discardable images metadata.
   const LayerTreeSettings& settings = layer_tree_host()->GetSettings();
@@ skipping 49 matching lines @@
     SetNeedsPushProperties();
   } else {
     // If this invalidation did not affect the recording source, then it can be
     // cleared as an optimization.
     last_updated_invalidation_.Clear();
   }
 
   return updated;
 }
 
-void PictureLayer::SetLayerMaskType(Layer::LayerMaskType mask_type) {
+void PictureLayer::SetLayerMaskType(LayerMaskType mask_type) {
   mask_type_ = mask_type;
 }
 
 sk_sp<SkPicture> PictureLayer::GetPicture() const {
   // We could either flatten the RecordingSource into a single SkPicture, or
   // paint a fresh one depending on what we intend to do with it.  For now we
   // just paint a fresh one to get consistent results.
   if (!DrawsContent())
     return nullptr;
 
@@ skipping 75 matching lines @@
     picture_layer_inputs_.display_list = nullptr;
     picture_layer_inputs_.painter_reported_memory_usage = 0;
   }
 }
 
 const DisplayItemList* PictureLayer::GetDisplayItemList() {
   return picture_layer_inputs_.display_list.get();
 }
 
 }  // namespace cc