cc: Route offscreen context creation for compositor to the browser.

content/common/gpu/client/context_provider_command_buffer.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/common/gpu/client/context_provider_command_buffer.h"
+
+#include "webkit/gpu/grcontext_for_webgraphicscontext3d.h"
+
+namespace content {
+
+class ContextProviderCommandBuffer::LostContextCallbackProxy
+    : public WebKit::WebGraphicsContext3D::WebGraphicsContextLostCallback {
+ public:
+  LostContextCallbackProxy(ContextProviderCommandBuffer* provider)
+      : provider_(provider) {
+    provider_->context3d_->setContextLostCallback(this);
+  }
+
+  virtual void onContextLost() {
+    provider_->OnLostContext();
+  }
+
+ private:
+  ContextProviderCommandBuffer* provider_;
+};
+
+class ContextProviderCommandBuffer::MemoryAllocationCallbackProxy
+    : public WebKit::WebGraphicsContext3D::
+          WebGraphicsMemoryAllocationChangedCallbackCHROMIUM {
+ public:
+  MemoryAllocationCallbackProxy(ContextProviderCommandBuffer* provider)
+      : provider_(provider) {
+    provider_->context3d_->setMemoryAllocationChangedCallbackCHROMIUM(this);
+  }
+
+  void onMemoryAllocationChanged(WebKit::WebGraphicsMemoryAllocation alloc) {
+    provider_->OnMemoryAllocationChanged(!!alloc.gpuResourceSizeInBytes);
+  }
+
+ private:
+  ContextProviderCommandBuffer* provider_;
+};
+
+ContextProviderCommandBuffer::ContextProviderCommandBuffer()
+    : destroyed_(false) {
+}
+
+ContextProviderCommandBuffer::~ContextProviderCommandBuffer() {}
+
+bool ContextProviderCommandBuffer::InitializeOnMainThread() {
+  if (destroyed_)
+    return false;
+  if (context3d_)
+    return true;
+
+  context3d_ = CreateOffscreenContext3d().Pass();
+  destroyed_ = !context3d_;
+  return !!context3d_;
+}
+
+bool ContextProviderCommandBuffer::BindToCurrentThread() {
+  if (lost_context_callback_proxy_)
+    return true;
+
+  bool result = context3d_->makeContextCurrent();
+  lost_context_callback_proxy_.reset(new LostContextCallbackProxy(this));
+  return result;
+}
+
+WebGraphicsContext3DCommandBufferImpl*
+ContextProviderCommandBuffer::Context3d() {
+  return context3d_.get();
+}
+
+class GrContext* ContextProviderCommandBuffer::GrContext() {
+  if (gr_context_)
+    return gr_context_->get();
+
+  gr_context_.reset(
+      new webkit::gpu::GrContextForWebGraphicsContext3D(context3d_.get()));
+  memory_allocation_callback_proxy_.reset(
+      new MemoryAllocationCallbackProxy(this));
+  return gr_context_->get();
+}
+
+void ContextProviderCommandBuffer::VerifyContexts() {
+  if (!destroyed_ && context3d_->isContextLost())
+    OnLostContext();
+}
+
+void ContextProviderCommandBuffer::OnLostContext() {
+  destroyed_ = true;

[piman, 2013/02/21 22:49:48]

The pattern is a bit iffy because you set this on the impl thread but test this
on the main thread, without locks (meaning technically the behavior is
undefined). Just adding a lock should do it I think.

The same is true of most of the ContextProvider implementations in this CL.

[danakj, 2013/02/22 01:56:31]

Done, and thanks for the explanations!

Renamed all the destroyed() functions to DestroyedOnMainThread() to make this
all more obvious too.

+}
+
+void ContextProviderCommandBuffer::OnMemoryAllocationChanged(
+    bool nonzero_allocation) {
+  if (gr_context_)
+    gr_context_->SetMemoryLimit(nonzero_allocation);
+}
+
+}  // namespace content