gpu: Introduce GpuChannelEstablishFactory.

gpu/ipc/client/gpu_channel_host.cc

Index: gpu/ipc/client/gpu_channel_host.cc
diff --git a/gpu/ipc/client/gpu_channel_host.cc b/gpu/ipc/client/gpu_channel_host.cc
index beeaa15bfd167cb62ac35d4eeb961cd92a688723..cc479d9e70dbc924f51f35b8c34364b6814607ff 100644
--- a/gpu/ipc/client/gpu_channel_host.cc
+++ b/gpu/ipc/client/gpu_channel_host.cc
@@ -27,8 +27,21 @@ namespace {
 // Global atomic to generate unique transfer buffer IDs.
 base::StaticAtomicSequenceNumber g_next_transfer_buffer_id;
 
+GpuChannelEstablishFactory* g_creator_factory = nullptr;

[piman, 2016/08/02 03:14:45]

I would like to avoid globals in GPU code. This breaks for e.g. single process
mode.
Can we instead inject the Factory where it's needed?

+
 }  // namespace
 
+void GpuChannelEstablishFactory::SetInstance(
+    GpuChannelEstablishFactory* factory) {
+  DCHECK(!g_creator_factory || !factory)
+      << "You cannot set a new factory while an old factory is still alive.";
+  g_creator_factory = factory;
+}
+
+GpuChannelEstablishFactory* GpuChannelEstablishFactory::GetInstance() {
+  return g_creator_factory;
+}
+
 GpuChannelHost::StreamFlushInfo::StreamFlushInfo()
     : next_stream_flush_id(1),
       flushed_stream_flush_id(0),