Re-land: cc: Implement shared worker contexts.

content/browser/compositor/gpu_process_transport_factory.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 "content/browser/compositor/gpu_process_transport_factory.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 226 matching lines @@
 #if defined(OS_CHROMEOS)
     LOG(FATAL) << "Unable to create a UI graphics context, and cannot use "
                << "software compositing on ChromeOS.";
 #endif
     create_gpu_output_surface = false;
   }
 
   scoped_refptr<ContextProviderCommandBuffer> context_provider;
   if (create_gpu_output_surface) {
     // Try to reuse existing worker context provider.
+    bool shared_worker_context_provider_lost = false;
     if (shared_worker_context_provider_) {
+      // Note: If context is lost, we delete reference after releasing the lock.
       base::AutoLock lock(*shared_worker_context_provider_->GetLock());
       if (shared_worker_context_provider_->ContextGL()
-              ->GetGraphicsResetStatusKHR() != GL_NO_ERROR)
-        shared_worker_context_provider_ = nullptr;
+              ->GetGraphicsResetStatusKHR() != GL_NO_ERROR) {
+        shared_worker_context_provider_lost = true;
+      }
     }
     scoped_refptr<GpuChannelHost> gpu_channel_host =
         BrowserGpuChannelHostFactory::instance()->GetGpuChannel();
     if (gpu_channel_host.get()) {
       context_provider = ContextProviderCommandBuffer::Create(
           GpuProcessTransportFactory::CreateContextCommon(gpu_channel_host,
                                                           data->surface_id),
           BROWSER_COMPOSITOR_ONSCREEN_CONTEXT);
       if (context_provider && !context_provider->BindToCurrentThread())
         context_provider = nullptr;
-      if (!shared_worker_context_provider_) {
+      if (!shared_worker_context_provider_ ||
+          shared_worker_context_provider_lost) {
         shared_worker_context_provider_ = ContextProviderCommandBuffer::Create(
             GpuProcessTransportFactory::CreateContextCommon(gpu_channel_host,
                                                             0),
             BROWSER_WORKER_CONTEXT);
         if (shared_worker_context_provider_ &&
             !shared_worker_context_provider_->BindToCurrentThread())
           shared_worker_context_provider_ = nullptr;
+        if (shared_worker_context_provider_)
+          shared_worker_context_provider_->SetupLock();
       }
     }
 
     bool created_gpu_browser_compositor =
         !!context_provider && !!shared_worker_context_provider_;
 
     UMA_HISTOGRAM_BOOLEAN("Aura.CreatedGpuBrowserCompositor",
                           created_gpu_browser_compositor);
 
     if (!created_gpu_browser_compositor) {
@@ skipping 346 matching lines @@
   FOR_EACH_OBSERVER(ImageTransportFactoryObserver,
                     observer_list_,
                     OnLostResources());
 
   // Kill things that use the shared context before killing the shared context.
   lost_gl_helper.reset();
   lost_shared_main_thread_contexts  = NULL;
 }
 
 }  // namespace content