Remove redundant codepath for webgl api blocking

content/common/gpu/gpu_command_buffer_stub.cc

 // Copyright (c) 2012 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.
 
 #include "content/common/gpu/gpu_command_buffer_stub.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 708 matching lines @@
   gpu::CommandBuffer::State state = command_buffer_->GetLastState();
   IPC::Message* msg = new GpuCommandBufferMsg_Destroyed(
       route_id_, state.context_lost_reason, state.error);
   msg->set_unblock(true);
   Send(msg);
 
   // Tell the browser about this context loss as well, so it can
   // determine whether client APIs like WebGL need to be immediately
   // blocked from automatically running.
   GpuChannelManager* gpu_channel_manager = channel_->gpu_channel_manager();
+  gpu::error::ContextLostReason error = state.context_lost_reason;
+  if (context_group_->feature_info()->workarounds().exit_on_context_lost) {
+    // The browser might only see one lost context if we force GPU process
+    // shutdown, so make sure it treats it seriously enough wrt 3D api blocking.

[no sievers, 2016/03/21 18:31:15]

Though there's probably a cleaner way to just handle this in the browser-side
logic.

[Ken Russell (switch to Gerrit), 2016/03/21 23:53:01]

Very nice. Thank you for tracking down the need to add this. With this change,
the "Rats!" infobar is showing up reliably, and properly, on Windows. Tested by
doing the following steps repeatedly:

Visiting:

https://www.khronos.org/registry/webgl/sdk/tests/extra/slow-shader-example.html

waiting for "Rats!", then visiting:

https://www.khronos.org/registry/webgl/sdk/tests/extra/canvas-compositing-tes...

and alternately ignoring and reloading the page via the infobar.

+    error = gpu::error::kUnknown;
+  }
   gpu_channel_manager->delegate()->DidLoseContext(
-      (surface_handle_ == gpu::kNullSurfaceHandle), state.context_lost_reason,
-      active_url_);
+      (surface_handle_ == gpu::kNullSurfaceHandle), error, active_url_);
 
   CheckContextLost();
 }
 
 void GpuCommandBufferStub::OnSchedulingChanged(bool scheduled) {
   TRACE_EVENT1("gpu", "GpuCommandBufferStub::OnSchedulingChanged", "scheduled",
                scheduled);
   channel_->OnStreamRescheduled(stream_id_, scheduled);
 }
 
@@ skipping 391 matching lines @@
                                                     result));
 }
 
 void GpuCommandBufferStub::SendUpdateVSyncParameters(base::TimeTicks timebase,
                                                      base::TimeDelta interval) {
   Send(new GpuCommandBufferMsg_UpdateVSyncParameters(route_id_, timebase,
                                                      interval));
 }
 
 }  // namespace content