WIP GPU scheduler + delayed activation / tile draw

gpu/command_buffer/service/command_executor.h

Index: gpu/command_buffer/service/command_executor.h
diff --git a/gpu/command_buffer/service/command_executor.h b/gpu/command_buffer/service/command_executor.h
index 7493d4f6244cea0df0170dc5314b00a3c6093c31..61c41b3887b3da52088e02d87825027ee63e2a5f 100644
--- a/gpu/command_buffer/service/command_executor.h
+++ b/gpu/command_buffer/service/command_executor.h
@@ -10,11 +10,8 @@
 #include <memory>
 #include <queue>
 
-#include "base/atomic_ref_count.h"
-#include "base/atomicops.h"
 #include "base/callback.h"
 #include "base/macros.h"
-#include "base/memory/ref_counted.h"
 #include "base/memory/shared_memory.h"
 #include "base/memory/weak_ptr.h"
 #include "gpu/command_buffer/service/cmd_buffer_engine.h"
@@ -25,22 +22,6 @@
 
 namespace gpu {
 
-class PreemptionFlag : public base::RefCountedThreadSafe<PreemptionFlag> {
- public:
-  PreemptionFlag() : flag_(0) {}
-
-  bool IsSet() { return !base::AtomicRefCountIsZero(&flag_); }
-  void Set() { base::AtomicRefCountInc(&flag_); }
-  void Reset() { base::subtle::NoBarrier_Store(&flag_, 0); }
-
- private:
-  base::AtomicRefCount flag_;
-
-  ~PreemptionFlag() {}
-
-  friend class base::RefCountedThreadSafe<PreemptionFlag>;
-};
-
 // This class schedules commands that have been flushed. They are received via
 // a command buffer and forwarded to a command parser. TODO(apatrick): This
 // class should not know about the decoder. Do not add additional dependencies
@@ -57,9 +38,10 @@ class GPU_EXPORT CommandExecutor
 
   void PutChanged();
 
-  void SetPreemptByFlag(scoped_refptr<PreemptionFlag> flag) {
-    preemption_flag_ = flag;
-  }
+  // This callback is checked regularly and execution is stopped if it returns
+  // true.
+  typedef base::Callback<bool(void)> PreemptionCallback;
+  void SetPreemptionCallback(const PreemptionCallback& callback);
 
   // Sets whether commands should be processed by this scheduler. Setting to
   // false unschedules. Setting to true reschedules.
@@ -122,10 +104,10 @@ class GPU_EXPORT CommandExecutor
   // Whether the scheduler is currently able to process more commands.
   bool scheduled_;
 
+  PreemptionCallback preemption_callback_;
+
   base::Closure command_processed_callback_;
 
-  // If non-NULL and |preemption_flag_->IsSet()|, exit PutChanged early.
-  scoped_refptr<PreemptionFlag> preemption_flag_;
   bool was_preempted_;
 
   DISALLOW_COPY_AND_ASSIGN(CommandExecutor);