cc: Add null checks for GrContext created by ContextProviderCommandBuffer.

content/common/gpu/client/context_provider_command_buffer.cc

Index: content/common/gpu/client/context_provider_command_buffer.cc
diff --git a/content/common/gpu/client/context_provider_command_buffer.cc b/content/common/gpu/client/context_provider_command_buffer.cc
index eb7096499b2d23d29552e8c61b652968f97e7267..013aef4865a8e68e70c97f9dd377f9e47ec6224e 100644
--- a/content/common/gpu/client/context_provider_command_buffer.cc
+++ b/content/common/gpu/client/context_provider_command_buffer.cc
@@ -134,11 +134,14 @@ class GrContext* ContextProviderCommandBuffer::GrContext() {
   if (gr_context_)
     return gr_context_->get();
 
+  // If 3d context is lost, skip trying to make a GrContext which could fail.
+  if (IsContextLost())
+    return nullptr;
+
   gr_context_.reset(new GrContextForWebGraphicsContext3D(context3d_.get()));
 
-  // If GlContext is already lost, also abandon the new GrContext.
-  if (IsContextLost())
-    gr_context_->get()->abandonContext();
+  // GrContext creation should not fail with a valid context.

[piman, 2015/05/12 22:06:11]

I'm not sure that's true. IsContextLost() is fundamentally racy, the context
might be lost right after it returned false.

A lost context is still a usable c++ object with all methods being functional
(if only return errors and failing GL calls). Couldn't we do the same with
GrContext?

+  DCHECK(gr_context_->get());
 
   return gr_context_->get();
 }