blimp: Set up the CompositorDependencies for blimp in Chrome.

chrome/browser/android/blimp/chrome_compositor_dependencies.h

+// Copyright 2016 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.
+
+#ifndef CHROME_BROWSER_ANDROID_BLIMP_CHROME_COMPOSITOR_DEPENDENCIES_H_
+#define CHROME_BROWSER_ANDROID_BLIMP_CHROME_COMPOSITOR_DEPENDENCIES_H_
+
+#include <list>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "blimp/client/public/compositor/compositor_dependencies.h"
+
+namespace ui {
+class ContextProviderFactory;
+}  // namespace ui
+
+// A wrapper for the Blimp compositor dependencies that passes through to the
+// ui::ContextProviderFactory. The ContextProviderFactory must outlive this
+// class.
+class ChromeCompositorDependencies
+    : public blimp::client::CompositorDependencies {
+ public:
+  ChromeCompositorDependencies(
+      ui::ContextProviderFactory* context_provider_factory);
+  ~ChromeCompositorDependencies() override;
+
+  // CompositorDependencies implementation.
+  cc::LayerTreeSettings* GetLayerTreeSettings() override;
+  gpu::GpuMemoryBufferManager* GetGpuMemoryBufferManager() override;
+  cc::SurfaceManager* GetSurfaceManager() override;
+  uint32_t AllocateSurfaceClientId() override;
+  void GetContextProviders(const ContextProviderCallback& callback) override;
+
+ private:
+  void OnWorkerContextCreated(
+      const scoped_refptr<cc::ContextProvider>& worker_context);
+
+  void HandleCompositorContextRequest(const ContextProviderCallback& callback);
+
+  ui::ContextProviderFactory* context_provider_factory_;
+
+  bool worker_context_request_pending_;

[David Trainor- moved to gerrit, 2016/08/31 00:28:58]

Add some comments around why we're doing it this way and how it works.

[Khushal, 2016/08/31 21:22:51]

Done.

+
+  // Worker context shared across all Blimp Compositors.
+  scoped_refptr<cc::ContextProvider> shared_main_thread_worker_context_;
+
+  std::list<ContextProviderCallback> pending_requests_;
+
+  base::WeakPtrFactory<ChromeCompositorDependencies> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeCompositorDependencies);
+};
+
+#endif  // CHROME_BROWSER_ANDROID_BLIMP_CHROME_COMPOSITOR_DEPENDENCIES_H_