Re-land: cc: Use worker context for one-copy tile initialization.

cc/output/output_surface.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 "cc/output/output_surface.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
 #include "base/thread_task_runner_handle.h"
@@ skipping 89 matching lines @@
                                       resourceless_software_draw);
 }
 
 OutputSurface::~OutputSurface() {
   if (context_provider_.get()) {
     context_provider_->SetLostContextCallback(
         ContextProvider::LostContextCallback());
     context_provider_->SetMemoryPolicyChangedCallback(
         ContextProvider::MemoryPolicyChangedCallback());
   }
-  if (worker_context_provider_.get()) {
-    worker_context_provider_->SetLostContextCallback(
-        ContextProvider::LostContextCallback());
-  }
 }
 
 bool OutputSurface::HasExternalStencilTest() const {
   return external_stencil_test_enabled_;
 }
 
 bool OutputSurface::BindToClient(OutputSurfaceClient* client) {
   DCHECK(client);
   client_ = client;
   bool success = true;
 
   if (context_provider_.get()) {
     success = context_provider_->BindToCurrentThread();
     if (success) {
       context_provider_->SetLostContextCallback(base::Bind(
           &OutputSurface::DidLoseOutputSurface, base::Unretained(this)));
       context_provider_->SetMemoryPolicyChangedCallback(
           base::Bind(&OutputSurface::SetMemoryPolicy, base::Unretained(this)));
     }
   }
 
   if (success && worker_context_provider_.get()) {
     success = worker_context_provider_->BindToCurrentThread();
-    if (success) {
+    if (success)
       worker_context_provider_->SetupLock();
-      // The destructor resets the context lost callback, so base::Unretained
-      // is safe, as long as the worker threads stop using the context before
-      // the output surface is destroyed.
-      worker_context_provider_->SetLostContextCallback(base::Bind(
-          &OutputSurface::DidLoseOutputSurface, base::Unretained(this)));
-    }
   }
 
   if (!success)
     client_ = NULL;
 
   return success;
 }
 
 void OutputSurface::EnsureBackbuffer() {
   if (software_device_)
@@ skipping 55 matching lines @@
 OverlayCandidateValidator* OutputSurface::GetOverlayCandidateValidator() const {
   return nullptr;
 }
 
 void OutputSurface::SetWorkerContextShouldAggressivelyFreeResources(
     bool aggressively_free_resources) {
   TRACE_EVENT1("cc",
                "OutputSurface::SetWorkerContextShouldAggressivelyFreeResources",
                "aggressively_free_resources", aggressively_free_resources);
   if (auto* context_provider = worker_context_provider()) {
-    // The context lock must be held while accessing the worker context.
-    base::AutoLock context_lock(*context_provider->GetLock());
-
-    // Allow context to bind to current thread.
-    context_provider->DetachFromThread();
+    ContextProvider::ScopedContextLock scoped_context(context_provider);
 
     if (aggressively_free_resources) {
       context_provider->DeleteCachedResources();
     }
 
     if (auto* context_support = context_provider->ContextSupport()) {
       context_support->SetAggressivelyFreeResources(
           aggressively_free_resources);
     }
-
-    // Allow context to bind to other threads.
-    context_provider->DetachFromThread();
   }
 }
 
 bool OutputSurface::SurfaceIsSuspendForRecycle() const {
   return false;
 }
 
 }  // namespace cc