WIP - Gutterless resize on Windows

content/common/gpu/client/gpu_channel_host.cc

Index: content/common/gpu/client/gpu_channel_host.cc
diff --git a/content/common/gpu/client/gpu_channel_host.cc b/content/common/gpu/client/gpu_channel_host.cc
index 80dfe0a48a074fe5ecd3040dd6a5c9e2361922f6..a398aad329a883a521af06ebf01bfe92a28f07b5 100644
--- a/content/common/gpu/client/gpu_channel_host.cc
+++ b/content/common/gpu/client/gpu_channel_host.cc
@@ -22,6 +22,7 @@
 
 #if defined(OS_WIN) || defined(OS_MACOSX)
 #include "content/public/common/sandbox_init.h"
+#include "ui/base/window_resize_helper.h"
 #endif
 
 using base::AutoLock;
@@ -317,10 +318,26 @@ void GpuChannelHost::AddRoute(
     int route_id, base::WeakPtr<IPC::Listener> listener) {
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner =
       factory_->GetIOThreadTaskRunner();
+
+#if defined(OS_MACOSX) || defined(OS_WIN)
+  scoped_refptr<base::SingleThreadTaskRunner> thread_task_runner;
+  if (factory_->IsMainThread()) {
+    // If we're adding a route to the main UI thread, we need to use the
+    // WindowResizeHelper's task runner, otherwise Gpu Channel messages will be
+    // blocked during a resize and we won't recieve the swap complete signal.
+    thread_task_runner = ui::WindowResizeHelper::Get()->task_runner();

[piman, 2015/12/11 07:53:12]

This code (GpuChannelHost) is used by both the renderer and the browser, so it's
not appropriate to always use WindowResizeHelper here.
My suggestion is to have the factory (which is different between the 2 cases)
provide the TaskRunner.

[ericrk, 2015/12/15 00:25:03]

done - good point - was thinking that was what IsMainThread meant, but realize I
misread this.

+  } else {
+    thread_task_runner = base::ThreadTaskRunnerHandle::Get();
+  }
+#else
+  scoped_refptr<base::SingleThreadTaskRunner> thread_task_runner =
+      base::ThreadTaskRunnerHandle::Get();
+#endif
+
   io_task_runner->PostTask(FROM_HERE,
                            base::Bind(&GpuChannelHost::MessageFilter::AddRoute,
                                       channel_filter_.get(), route_id, listener,
-                                      base::ThreadTaskRunnerHandle::Get()));
+                                      thread_task_runner));
 }
 
 void GpuChannelHost::RemoveRoute(int route_id) {