views/mus: Fix some flaky crashes during test teardown.

ui/views/mus/surface_binding.cc

 // Copyright 2015 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 "ui/views/mus/surface_binding.h"
 
 #include <stdint.h>
 
 #include <map>
 #include <utility>
@@ skipping 80 matching lines @@
     (*window_map)[connection] = new PerConnectionState(connector, connection);
     (*window_map)[connection]->Init();
   }
   return (*window_map)[connection];
 }
 
 std::unique_ptr<cc::OutputSurface>
 SurfaceBinding::PerConnectionState::CreateOutputSurface(
     mus::Window* window,
     mus::mojom::SurfaceType surface_type) {
+  if (gpu_.encountered_error())
+    return nullptr;
   // TODO(sky): figure out lifetime here. Do I need to worry about the return
   // value outliving this?
   mus::mojom::CommandBufferPtr cb;
   gpu_->CreateOffscreenGLES2Context(GetProxy(&cb));
 
   scoped_refptr<cc::ContextProvider> context_provider(
       new mus::ContextProvider(cb.PassInterface().PassHandle()));
   return base::WrapUnique(new mus::OutputSurface(
       context_provider, window->RequestSurface(surface_type)));
 }
 
 SurfaceBinding::PerConnectionState::PerConnectionState(
     shell::Connector* connector,
     mus::WindowTreeConnection* connection)
     : connector_(connector), connection_(connection) {}
 
 SurfaceBinding::PerConnectionState::~PerConnectionState() {
   ConnectionToStateMap* window_map = window_states.Pointer()->Get();
   DCHECK(window_map);
   DCHECK_EQ(this, (*window_map)[connection_]);
   window_map->erase(connection_);
   if (window_map->empty()) {
     delete window_map;
     window_states.Pointer()->Set(nullptr);
   }
 }
 
 void SurfaceBinding::PerConnectionState::Init() {
   connector_->ConnectToInterface("mojo:mus", &gpu_);
+  gpu_.set_connection_error_handler([]{});

[sadrul, 2016/05/18 20:00:19]

rockot@: This seems to be necessary for the change above to work (i.e. without
this, |gpu_.encountered_error()| doesn't seem to see any errors). I assume this
is unexpected? Any ideas/suggestions as to why this may be making a difference?

[sky, 2016/05/18 20:10:32]

This seems like a bug in the bindings code.

[Ken Rockot(use gerrit already), 2016/05/18 20:11:08]

Because we lazily set up the internal proxy in InterfacePtr, and
set_connection_error_handler is one of the calls which forces proxy setup.
+yzshen@ +amistry@ I remember that we made this change for a reason, but I don't
remember why. Why doesn't Bind also configure the proxy?

[sadrul, 2016/05/19 20:14:17]

OK. Sounds like this is not entirely unexpected, then. Can I add a TODO here and
refer to some bug (does one already exist?) so this doesn't get lost?

[sky, 2016/05/19 20:59:42]

Yes, go for it.

 }
 
 // SurfaceBinding --------------------------------------------------------------
 
 SurfaceBinding::SurfaceBinding(shell::Connector* connector,
                                mus::Window* window,
                                mus::mojom::SurfaceType surface_type)
     : window_(window),
       surface_type_(surface_type),
       state_(PerConnectionState::Get(connector, window->connection())) {}
 
 SurfaceBinding::~SurfaceBinding() {}
 
 std::unique_ptr<cc::OutputSurface> SurfaceBinding::CreateOutputSurface() {
   return state_->CreateOutputSurface(window_, surface_type_);
 }
 
 }  // namespace views