content: Fix Context creation logic in ContextProviderFactoryImpl.

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"
@@ skipping 13 matching lines @@
 
 struct SharedMemoryLimits;
 class GpuMemoryBufferManager;
 }  // namespace gpu
 
 namespace ui {
 
 // This class is not thread-safe and should only be accessed from the UI thread.
 class UI_ANDROID_EXPORT ContextProviderFactory {
  public:
+  enum class ContextCreationResult {
+    FAILURE_GPU_PROCESS_INITIALIZATION_FAILED,
+
+    // Used when the browser is shutting down. No more requests should be made

[David Trainor- moved to gerrit, 2016/08/18 17:49:43]

Should we enforce/DCHECK that we don't get calls after sending this?

[Khushal, 2016/08/18 18:29:13]

We can internally enforce that we are not getting any callbacks while we are
running the existing ones with a shutdown response. Should we also add a
DidShutdown() method to the factory that the caller should check before making a
request?

+    // after this.
+    FAILURE_BROWSER_SHUTDOWN,
+
+    // The GpuSurfaceHandle for the request was lost before the context could be
+    // created. This is used for on-screen context requests only.
+    FAILURE_GPU_SURFACE_HANDLE_LOST,
+
+    // Set if the Context creation was successful.
+    SUCCESS,
+  };
+
   using ContextProviderCallback =
-      base::Callback<void(const scoped_refptr<cc::ContextProvider>&)>;
+      base::Callback<void(const scoped_refptr<cc::ContextProvider>&,
+                          ContextCreationResult)>;
 
   enum class ContextType {
     BLIMP_RENDER_COMPOSITOR_CONTEXT,
     BLIMP_RENDER_WORKER_CONTEXT,
   };
 
   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(){};
 
   virtual scoped_refptr<cc::VulkanContextProvider>
   GetSharedVulkanContextProvider() = 0;
 
   // Creates an offscreen ContextProvider for the compositor. Any shared
   // contexts passed here *must* have been created using this factory.
-  // The callback may be triggered synchronously if possible, and will always
-  // have the context provider.
+  // The callback may be triggered synchronously if possible. If the context
+  // creation fails, a null context is passed with the specified reason.
   virtual void CreateOffscreenContextProvider(
       ContextType context_type,
       gpu::SharedMemoryLimits shared_memory_limits,
       gpu::gles2::ContextCreationAttribHelper attributes,
       bool support_locking,
       bool automatic_flushes,
       cc::ContextProvider* shared_context_provider,
       ContextProviderCallback result_callback) = 0;
 
   virtual cc::SurfaceManager* GetSurfaceManager() = 0;
 
   virtual uint32_t AllocateSurfaceClientId() = 0;
 
   virtual cc::SharedBitmapManager* GetSharedBitmapManager() = 0;
 
   virtual gpu::GpuMemoryBufferManager* GetGpuMemoryBufferManager() = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_ANDROID_CONTEXT_PROVIDER_FACTORY_H_