android: Pass cc::ContextProvider to VideoContextProvider.

content/browser/android/in_process/synchronous_compositor_factory_impl.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/android/in_process/synchronous_compositor_factory_impl.h"
 
 #include "base/command_line.h"
 #include "base/observer_list.h"
 #include "content/browser/android/in_process/synchronous_compositor_external_begin_frame_source.h"
 #include "content/browser/android/in_process/synchronous_compositor_impl.h"
@@ skipping 64 matching lines @@
   return scoped_ptr<WebGraphicsContext3DInProcessCommandBufferImpl>(
       WebGraphicsContext3DInProcessCommandBufferImpl::WrapContext(
           context.Pass(), attributes));
 }
 
 }  // namespace
 
 class SynchronousCompositorFactoryImpl::VideoContextProvider
     : public StreamTextureFactorySynchronousImpl::ContextProvider {
  public:
-  VideoContextProvider(
-      scoped_ptr<gpu::GLInProcessContext> gl_in_process_context)
-      : gl_in_process_context_(gl_in_process_context.get()) {
-    context_provider_ = webkit::gpu::ContextProviderInProcess::Create(
-        WrapContext(gl_in_process_context.Pass(), GetDefaultAttribs()),
-        "Video-Offscreen-main-thread");
+  VideoContextProvider(gpu::GLInProcessContext* gl_in_process_context,
+                       scoped_refptr<cc::ContextProvider> context_provider)
+      : gl_in_process_context_(gl_in_process_context),
+        context_provider_(context_provider) {
     context_provider_->BindToCurrentThread();
   }
 
   scoped_refptr<gfx::SurfaceTexture> GetSurfaceTexture(
       uint32 stream_id) override {
     return gl_in_process_context_->GetSurfaceTexture(stream_id);
   }
 
   gpu::gles2::GLES2Interface* ContextGL() override {
     return context_provider_->ContextGL();
@@ skipping 10 matching lines @@
   void RestoreContext() {
     FOR_EACH_OBSERVER(StreamTextureFactoryContextObserver,
                       observer_list_,
                       ResetStreamTextureProxy());
   }
 
  private:
   friend class base::RefCountedThreadSafe<VideoContextProvider>;
   ~VideoContextProvider() override {}
 
+  gpu::GLInProcessContext* gl_in_process_context_;

[boliu, 2015/04/08 20:24:26]

Why the reorder? In theory, this would lead to a moment during destruction where
gl_in_process_context_ is a dangling pointer, since member variables are
destroyed in the reverse order they are declared.

   scoped_refptr<cc::ContextProvider> context_provider_;
-  gpu::GLInProcessContext* gl_in_process_context_;
   ObserverList<StreamTextureFactoryContextObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoContextProvider);
 };
 
 
 SynchronousCompositorFactoryImpl::SynchronousCompositorFactoryImpl()
     : record_full_layer_(true),
       num_hardware_compositors_(0) {
   SynchronousCompositorFactory::SetInstance(this);
@@ skipping 122 matching lines @@
         scoped_refptr<StreamTextureFactorySynchronousImpl::ContextProvider>();
   }
 
   if (!video_context_provider_.get()) {
     DCHECK(service_.get());
 
     blink::WebGraphicsContext3D::Attributes attributes = GetDefaultAttribs();
     attributes.shareResources = false;
     // This needs to run in on-screen |service_| context due to SurfaceTexture
     // limitations.
-    video_context_provider_ = new VideoContextProvider(CreateContextHolder(
-        attributes, service_, gpu::GLInProcessContextSharedMemoryLimits(),
-        false));
+    scoped_ptr<gpu::GLInProcessContext> context =
+        CreateContextHolder(attributes, service_,
+                            gpu::GLInProcessContextSharedMemoryLimits(), false);
+    video_context_provider_ = new VideoContextProvider(
+        context.get(), webkit::gpu::ContextProviderInProcess::Create(

[boliu, 2015/04/08 20:24:26]

Just save the raw pointer in a local variable. This is really brittle if someone
reorders the arguments in the future, and don't look closely at what this is
doing.

[tfarina, 2015/04/08 20:26:25]

Unfortunately that didn't work very well with WrapContext, which takes a
scoped_ptr, not a raw pointer. Am I missing something?

[boliu, 2015/04/08 20:29:58]

This should work (ignore poor formatting):

    scoped_ptr<gpu::GLInProcessContext> context =
        CreateContextHolder(attributes, service_,
                            gpu::GLInProcessContextSharedMemoryLimits(), false);
    gpu::GLInProcessContext* context_ptr = context.get();
    video_context_provider_ = new VideoContextProvider(
        webkit::gpu::ContextProviderInProcess::Create(
                           WrapContext(context.Pass(), GetDefaultAttribs()),
                           "Video-Offscreen-main-thread"), context_ptr);

[tfarina, 2015/04/08 20:56:46]

Cool! thanks. Done.

+                           WrapContext(context.Pass(), GetDefaultAttribs()),
+                           "Video-Offscreen-main-thread"));
   }
   return video_context_provider_;
 }
 
 void SynchronousCompositorFactoryImpl::SetDeferredGpuService(
     scoped_refptr<gpu::InProcessCommandBuffer::Service> service) {
   DCHECK(!service_.get());
   service_ = service;
 }
 
 void SynchronousCompositorFactoryImpl::SetRecordFullDocument(
     bool record_full_document) {
   record_full_layer_ = record_full_document;
 }
 
 }  // namespace content