GPU: Only allow the UI channel to preempt if all stubs are scheduled.

gpu/command_buffer/service/gpu_scheduler.cc

Index: gpu/command_buffer/service/gpu_scheduler.cc
diff --git a/gpu/command_buffer/service/gpu_scheduler.cc b/gpu/command_buffer/service/gpu_scheduler.cc
index 78739dca5fcf9b0899c97e2aeb15b59ec0cdc6bd..03f61a2cf4bae32e72e0886a264cc15f166e2915 100644
--- a/gpu/command_buffer/service/gpu_scheduler.cc
+++ b/gpu/command_buffer/service/gpu_scheduler.cc
@@ -156,8 +156,9 @@ void GpuScheduler::SetScheduled(bool scheduled) {
       }
 #endif
     }
-
     ++unscheduled_count_;
+    if (!descheduled_callback_.is_null())

[piman, 2013/02/27 21:54:43]

call this only if unscheduled_count_ is 1 (otherwise, seems overkill)

[jonathan.backer, 2013/02/28 21:43:56]

Done.

+      descheduled_callback_.Run();
   }
 }
 
@@ -175,6 +176,11 @@ void GpuScheduler::SetScheduledCallback(
   scheduled_callback_ = scheduled_callback;
 }
 
+void GpuScheduler::SetDescheduledCallback(
+    const base::Closure& descheduled_callback) {
+  descheduled_callback_ = descheduled_callback;
+}
+
 Buffer GpuScheduler::GetSharedMemoryBuffer(int32 shm_id) {
   return command_buffer_->GetTransferBuffer(shm_id);
 }