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

gpu/command_buffer/service/gpu_scheduler.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 "gpu/command_buffer/service/gpu_scheduler.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/debug/trace_event.h"
@@ skipping 138 matching lines @@
         // delayed task that it will force it back into a scheduled state after
         // a timeout. This should only be necessary on pre-Vista.
         MessageLoop::current()->PostDelayedTask(
             FROM_HERE,
             base::Bind(&GpuScheduler::RescheduleTimeOut,
                        reschedule_task_factory_.GetWeakPtr()),
             base::TimeDelta::FromMilliseconds(kRescheduleTimeOutDelay));
       }
 #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();
   }
 }
 
 bool GpuScheduler::IsScheduled() {
   return unscheduled_count_ == 0;
 }
 
 bool GpuScheduler::HasMoreWork() {
   return !unschedule_fences_.empty() ||
          (decoder_ && decoder_->ProcessPendingQueries());
 }
 
 void GpuScheduler::SetScheduledCallback(
     const base::Closure& scheduled_callback) {
   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);
 }
 
 void GpuScheduler::set_token(int32 token) {
   command_buffer_->SetToken(token);
 }
 
 bool GpuScheduler::SetGetBuffer(int32 transfer_buffer_id) {
   Buffer ring_buffer = command_buffer_->GetTransferBuffer(transfer_buffer_id);
@@ skipping 92 matching lines @@
 }
 
 GpuScheduler::UnscheduleFence::UnscheduleFence(
     gfx::GLFence* fence_, base::Closure task_): fence(fence_), task(task_) {
 }
 
 GpuScheduler::UnscheduleFence::~UnscheduleFence() {
 }
 
 }  // namespace gpu