CC: Plumb LayerSettings parameter for cc::Layer construction.

android_webview/browser/hardware_renderer.cc

 // Copyright 2014 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 "android_webview/browser/hardware_renderer.h"
 
 #include "android_webview/browser/aw_gl_surface.h"
 #include "android_webview/browser/aw_render_thread_context_provider.h"
 #include "android_webview/browser/child_frame.h"
 #include "android_webview/browser/deferred_gpu_command_service.h"
 #include "android_webview/browser/parent_compositor_draw_constraints.h"
 #include "android_webview/browser/parent_output_surface.h"
 #include "android_webview/browser/shared_renderer_state.h"
 #include "android_webview/public/browser/draw_gl.h"
 #include "base/auto_reset.h"
+#include "base/lazy_instance.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/layers/delegated_frame_provider.h"
 #include "cc/layers/delegated_renderer_layer.h"
 #include "cc/layers/layer.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/output_surface.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_settings.h"
 #include "gpu/command_buffer/client/gl_in_process_context.h"
 #include "gpu/command_buffer/common/gles2_cmd_utils.h"
 #include "ui/gfx/frame_time.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/transform.h"
 #include "ui/gl/gl_bindings.h"
 
 namespace android_webview {
 
+base::LazyInstance<cc::LayerSettings> g_layer_settings =
+    LAZY_INSTANCE_INITIALIZER;

[boliu, 2015/05/20 15:51:02]

Lazy instance feels over kill here. I don't think constructing a LayerSettings
is expensive?

And should use a function if the purpose is to unify LayerSettings creation,
since lazy instance doesn't have the opportunity to change any of the settings
from default.

[loyso (OOO), 2015/05/21 05:12:35]

Yes, thread-safety is over kill here. Our style guide says: "Static or global
variables of class type are forbidden". It allows only structs of POD (which is
better to be updated in C++11 trivial/non-trivial terms). I could replace lazy
instances with simple static functions everywhere.

Linters are ok with "cc::LayerSettings g_layer_settings" except that I need to
remove the empty destructor.

What do you think?

[boliu, 2015/05/21 05:23:32]

That's definitely not allowed. Having the constructor means it creates a static
initializer. And not having a constructor means the members are not initialized.
Either just create LayerSettings on the stack where it's needed. Or create a
global function, in an anonymous namespace, that constructs and returns a *copy*
of LayerSettings.

No threading issues if you never have a global instance.

+
 HardwareRenderer::HardwareRenderer(SharedRendererState* state)
     : shared_renderer_state_(state),
       last_egl_context_(eglGetCurrentContext()),
       stencil_enabled_(false),
       viewport_clip_valid_for_dcheck_(false),
       gl_surface_(new AwGLSurface),
-      root_layer_(cc::Layer::Create()),
+      root_layer_(cc::Layer::Create(g_layer_settings.Get())),
       resource_collection_(new cc::DelegatedFrameResourceCollection),
       output_surface_(NULL) {
   DCHECK(last_egl_context_);
 
   resource_collection_->SetClient(this);
 
   cc::LayerTreeSettings settings;
 
   // Should be kept in sync with compositor_impl_android.cc.
   settings.renderer_settings.allow_antialiasing = false;
@@ skipping 74 matching lines @@
   frame_size_ = frame_size;
 
   if (!frame_provider_.get() || size_changed) {
     if (delegated_layer_.get()) {
       delegated_layer_->RemoveFromParent();
     }
 
     frame_provider_ = new cc::DelegatedFrameProvider(
         resource_collection_.get(), frame->delegated_frame_data.Pass());
 
-    delegated_layer_ = cc::DelegatedRendererLayer::Create(frame_provider_);
+    delegated_layer_ = cc::DelegatedRendererLayer::Create(
+        g_layer_settings.Get(), frame_provider_);
     delegated_layer_->SetBounds(frame_size_);
     delegated_layer_->SetIsDrawable(true);
 
     root_layer_->AddChild(delegated_layer_);
   } else {
     frame_provider_->SetFrameData(frame->delegated_frame_data.Pass());
   }
 }
 
 void HardwareRenderer::DrawGL(bool stencil_enabled,
@@ skipping 62 matching lines @@
 }
 
 void HardwareRenderer::UnusedResourcesAreAvailable() {
   cc::ReturnedResourceArray returned_resources;
   resource_collection_->TakeUnusedResourcesForChildCompositor(
       &returned_resources);
   shared_renderer_state_->InsertReturnedResourcesOnRT(returned_resources);
 }
 
 }  // namespace android_webview