WIP GPU scheduler + delayed activation / tile draw

gpu/command_buffer/service/command_executor.cc

Index: gpu/command_buffer/service/command_executor.cc
diff --git a/gpu/command_buffer/service/command_executor.cc b/gpu/command_buffer/service/command_executor.cc
index ff7a910bf86a8263b70eae0440746003f5295e2b..0c4debec20bc329d9d71c9c018f8f96db33b5348 100644
--- a/gpu/command_buffer/service/command_executor.cc
+++ b/gpu/command_buffer/service/command_executor.cc
@@ -152,19 +152,26 @@ void CommandExecutor::SetCommandProcessedCallback(
   command_processed_callback_ = callback;
 }
 
+void CommandExecutor::SetPreemptionCallback(
+    const PreemptionCallback& callback) {
+  preemption_callback_ = callback;
+}
+
 bool CommandExecutor::IsPreempted() {
-  if (!preemption_flag_.get())
+  if (preemption_callback_.is_null())
     return false;
 
-  if (!was_preempted_ && preemption_flag_->IsSet()) {
+  bool preempt = preemption_callback_.Run();
+
+  if (!was_preempted_ && preempt) {
     TRACE_COUNTER_ID1("gpu", "CommandExecutor::Preempted", this, 1);
     was_preempted_ = true;
-  } else if (was_preempted_ && !preemption_flag_->IsSet()) {
+  } else if (was_preempted_ && !preempt) {
     TRACE_COUNTER_ID1("gpu", "CommandExecutor::Preempted", this, 0);
     was_preempted_ = false;
   }
 
-  return preemption_flag_->IsSet();
+  return preempt;
 }
 
 bool CommandExecutor::HasMoreIdleWork() const {