content: Add ContextProviderFactory to create a render ContextProvider.

ui/android/context_provider_factory.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 UI_ANDROID_CONTEXT_PROVIDER_FACTORY_H_
+#define UI_ANDROID_CONTEXT_PROVIDER_FACTORY_H_
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "ui/android/ui_android_export.h"
+
+namespace cc {
+class ContextProvider;
+class VulkanContextProvider;
+class SurfaceManager;
+}
+
+namespace ui {
+
+// This class is not thread-safe and should only be accessed from the UI thread.
+class UI_ANDROID_EXPORT ContextProviderFactory {
+ public:
+  struct ContextProviders {
+    ContextProviders();
+    ~ContextProviders();
+
+    scoped_refptr<cc::VulkanContextProvider> vulkan_context_provider;
+
+    scoped_refptr<cc::ContextProvider> compositor_context_provider;
+    scoped_refptr<cc::ContextProvider> worker_context_provider;
+  };
+
+  using ContextProviderCallback = base::Callback<void(const ContextProviders&)>;
+
+  static ContextProviderFactory* GetInstance();
+
+  // This should only be called once, on startup. Ownership remains with the
+  // caller.
+  static void SetInstance(ContextProviderFactory* context_provider_factory);
+
+  virtual ~ContextProviderFactory(){};

[no sievers, 2016/07/29 19:14:31]

nit: space in between () and {}

+
+  // Creates a ContextProvider with an offscreen context for a compositor
+  // rendering web content.
+  virtual void RequestRenderContextProvider(

[no sievers, 2016/07/29 19:14:31]

nit: maybe 'CreateOffscreenContextProvider()'?

+      ContextProviderCallback result_callback) = 0;
+
+  virtual cc::SurfaceManager* GetSurfaceManager() = 0;
+
+  virtual uint32_t AllocateSurfaceClientId() = 0;
+};
+
+}  // namespace ui
+
+#endif  // UI_ANDROID_CONTEXT_PROVIDER_FACTORY_H_