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

Necessary for uber-comp with --ui-prioritize-in-gpu-process. Currently will not affect preemption.

BUG=173650


Review URL: https://chromiumcodereview.appspot.com/12340118

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@185445 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 16 insertions, 12 deletions

diff --git a/gpu/command_buffer/service/gpu_scheduler.cc b/gpu/command_buffer/service/gpu_scheduler.cc
index 78739dc..61bdcf8 100644
--- a/gpu/command_buffer/service/gpu_scheduler.cc
+++ b/gpu/command_buffer/service/gpu_scheduler.cc
@@ -136,11 +136,12 @@ void GpuScheduler::SetScheduled(bool scheduled) {
       // state, cancel the task that would reschedule it after a timeout.
       reschedule_task_factory_.InvalidateWeakPtrs();
 
-      if (!scheduled_callback_.is_null())
-        scheduled_callback_.Run();
+      if (!scheduling_changed_callback_.is_null())
+        scheduling_changed_callback_.Run(true);
     }
   } else {
-    if (unscheduled_count_ == 0) {
+    ++unscheduled_count_;
+    if (unscheduled_count_ == 1) {
       TRACE_EVENT_ASYNC_BEGIN1("gpu", "ProcessingSwap", this,
                                "GpuScheduler", this);
 #if defined(OS_WIN)
@@ -155,9 +156,9 @@ void GpuScheduler::SetScheduled(bool scheduled) {
             base::TimeDelta::FromMilliseconds(kRescheduleTimeOutDelay));
       }
 #endif
+      if (!scheduling_changed_callback_.is_null())
+        scheduling_changed_callback_.Run(false);
     }
-
-    ++unscheduled_count_;
   }
 }
 
@@ -170,9 +171,9 @@ bool GpuScheduler::HasMoreWork() {
          (decoder_ && decoder_->ProcessPendingQueries());
 }
 
-void GpuScheduler::SetScheduledCallback(
-    const base::Closure& scheduled_callback) {
-  scheduled_callback_ = scheduled_callback;
+void GpuScheduler::SetSchedulingChangedCallback(
+    const SchedulingChangedCallback& callback) {
+  scheduling_changed_callback_ = callback;
 }
 
 Buffer GpuScheduler::GetSharedMemoryBuffer(int32 shm_id) {
diff --git a/gpu/command_buffer/service/gpu_scheduler.h b/gpu/command_buffer/service/gpu_scheduler.h
index 32a38b9..0e58d8c 100644
--- a/gpu/command_buffer/service/gpu_scheduler.h
+++ b/gpu/command_buffer/service/gpu_scheduler.h
@@ -76,9 +76,11 @@ class GPU_EXPORT GpuScheduler
   // Returns whether the scheduler needs to be polled again in the future.
   bool HasMoreWork();
 
-  // Sets a callback that is invoked just before scheduler is rescheduled.
-  // Takes ownership of callback object.
-  void SetScheduledCallback(const base::Closure& scheduled_callback);
+  typedef base::Callback<void(bool /* scheduled */)> SchedulingChangedCallback;
+
+  // Sets a callback that is invoked just before scheduler is rescheduled
+  // or descheduled. Takes ownership of callback object.
+  void SetSchedulingChangedCallback(const SchedulingChangedCallback& callback);
 
   // Implementation of CommandBufferEngine.
   virtual Buffer GetSharedMemoryBuffer(int32 shm_id) OVERRIDE;
@@ -146,7 +148,8 @@ class GPU_EXPORT GpuScheduler
   };
   std::queue<linked_ptr<UnscheduleFence> > unschedule_fences_;
 
-  base::Closure scheduled_callback_;
+  SchedulingChangedCallback scheduling_changed_callback_;
+  base::Closure descheduled_callback_;
   base::Closure command_processed_callback_;
 
   // If non-NULL and |preemption_flag_->IsSet()|, exit PutChanged early.