content: Fix Context creation logic in ContextProviderFactoryImpl.

ui/android/context_provider_factory.h

Index: ui/android/context_provider_factory.h
diff --git a/ui/android/context_provider_factory.h b/ui/android/context_provider_factory.h
index 8ad9d6f4a0c3eacef8a1e0982a974b337ceb4684..ba91f5eb0244e9bdd32a2ad4352b04e16ff82208 100644
--- a/ui/android/context_provider_factory.h
+++ b/ui/android/context_provider_factory.h
@@ -31,8 +31,18 @@ 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 ContextCreationFailureReason {
+    GPU_PROCESS_INITIALIZATION_FAILURE,
+    BROWSER_SHUTDOWN,
+    GPU_SURFACE_HANDLE_LOST,
+
+    // Set if the Context creation was successful.
+    FAILURE_NONE,

[no sievers, 2016/08/17 18:30:10]

nit: how about |ContextCreationResult| and _SUCCESS here?

[Khushal, 2016/08/17 21:24:56]

That's much better. Done.

+  };
+
   using ContextProviderCallback =
-      base::Callback<void(const scoped_refptr<cc::ContextProvider>&)>;
+      base::Callback<void(const scoped_refptr<cc::ContextProvider>&,
+                          ContextCreationFailureReason reason)>;
 
   enum class ContextType {
     BLIMP_RENDER_COMPOSITOR_CONTEXT,
@@ -52,8 +62,8 @@ class UI_ANDROID_EXPORT ContextProviderFactory {
 
   // 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,