content/blimp: Set up hooks for enabling LTHRemote in the renderer.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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 "content/renderer/gpu/render_widget_compositor.h"
 
 #include <stddef.h>
 #include <limits>
 #include <string>
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/synchronization/lock.h"
 #include "base/sys_info.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "cc/animation/animation_host.h"
 #include "cc/animation/animation_timeline.h"
 #include "cc/animation/layer_tree_mutator.h"
 #include "cc/base/switches.h"
+#include "cc/blimp/engine_picture_cache.h"
+#include "cc/blimp/image_serialization_processor.h"
+#include "cc/blimp/layer_tree_host_remote.h"
+#include "cc/blimp/remote_compositor_bridge.h"
 #include "cc/blink/web_layer_impl.h"
 #include "cc/debug/layer_tree_debug_state.h"
 #include "cc/debug/micro_benchmark.h"
 #include "cc/input/layer_selection_bound.h"
 #include "cc/layers/layer.h"
 #include "cc/output/begin_frame_args.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
 #include "cc/output/latency_info_swap_promise.h"
 #include "cc/output/swap_promise.h"
 #include "cc/proto/compositor_message.pb.h"
 #include "cc/resources/single_release_callback.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/trees/latency_info_swap_promise_monitor.h"
 #include "cc/trees/layer_tree_host_in_process.h"
 #include "cc/trees/remote_proto_channel.h"
 #include "content/common/content_switches_internal.h"
 #include "content/common/gpu/client/context_provider_command_buffer.h"
 #include "content/common/layer_tree_settings_factory.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
+#include "content/public/renderer/content_renderer_client.h"
 #include "content/renderer/gpu/render_widget_compositor_delegate.h"
 #include "content/renderer/input/input_handler_manager.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "third_party/WebKit/public/platform/WebCompositeAndReadbackAsyncCallback.h"
 #include "third_party/WebKit/public/platform/WebCompositorMutatorClient.h"
 #include "third_party/WebKit/public/platform/WebLayoutAndPaintAsyncCallback.h"
 #include "third_party/WebKit/public/platform/WebSize.h"
 #include "third_party/WebKit/public/platform/scheduler/renderer/renderer_scheduler.h"
 #include "third_party/WebKit/public/web/WebKit.h"
@@ skipping 166 matching lines @@
       threaded_(!!compositor_deps_->GetCompositorImplThreadTaskRunner()),
       never_visible_(false),
       layout_and_paint_async_callback_(nullptr),
       remote_proto_channel_receiver_(nullptr),
       weak_factory_(this) {}
 
 void RenderWidgetCompositor::Initialize(float device_scale_factor) {
   base::CommandLine* cmd = base::CommandLine::ForCurrentProcess();
   cc::LayerTreeSettings settings =
       GenerateLayerTreeSettings(*cmd, compositor_deps_, device_scale_factor);
+
+  if (cmd->HasSwitch(switches::kUseRemoteCompositing) &&
+      cmd->HasSwitch(switches::kUseLayerTreeHostRemote)) {
+    DCHECK(!threaded_);

[Wez, 2016/10/19 22:15:28]

nit: Command-line switches come from outside the process; what will happen if we
somehow get mismatched switches in a Release build? What is the failure mode
then?

[Khushal, 2016/10/20 01:29:33]

I'm not sure what you mean by mis-matched switches. The only thing this DCHECK
is verifying is that we did not create the compositor thread since that is also
done based on the kUseRemoteCompositing switch here,
https://cs.chromium.org/chromium/src/content/renderer/render_thread_impl.cc?s...

+
+    cc::LayerTreeHostRemote::InitParams params;
+    params.client = this;
+    params.main_task_runner =
+        compositor_deps_->GetCompositorMainThreadTaskRunner();
+    params.animation_host = cc::AnimationHost::CreateMainInstance();
+    params.remote_compositor_bridge =
+        GetContentClient()->renderer()->CreateRemoteCompositorBridge(
+            this, params.main_task_runner);
+    params.engine_picture_cache =
+        compositor_deps_->GetImageSerializationProcessor()
+            ->CreateEnginePictureCache();
+    params.settings = &settings;
+    layer_tree_host_ = base::MakeUnique<cc::LayerTreeHostRemote>(&params);
+    return;
+  }
+
   cc::LayerTreeHostInProcess::InitParams params;
   params.client = this;
   params.shared_bitmap_manager = compositor_deps_->GetSharedBitmapManager();
   params.gpu_memory_buffer_manager =
       compositor_deps_->GetGpuMemoryBufferManager();
   params.settings = &settings;
   params.task_graph_runner = compositor_deps_->GetTaskGraphRunner();
   params.main_task_runner =
       compositor_deps_->GetCompositorMainThreadTaskRunner();
   params.animation_host = cc::AnimationHost::CreateMainInstance();
@@ skipping 872 matching lines @@
     float device_scale) {
   layer_tree_host_->GetLayerTree()->SetPaintedDeviceScaleFactor(device_scale);
 }
 
 void RenderWidgetCompositor::SetDeviceColorSpace(
     const gfx::ColorSpace& color_space) {
   layer_tree_host_->GetLayerTree()->SetDeviceColorSpace(color_space);
 }
 
 }  // namespace content