Added disjoint context class which manages disjoints within gpu timing.

gpu/command_buffer/service/gpu_timing.h

Index: gpu/command_buffer/service/gpu_timing.h
diff --git a/gpu/command_buffer/service/gpu_timing.h b/gpu/command_buffer/service/gpu_timing.h
index 726ac4e5f776a19a466276edd017a4a48cfc0446..97cc3192c73947c6759ea49e6382411df6be9cd6 100644
--- a/gpu/command_buffer/service/gpu_timing.h
+++ b/gpu/command_buffer/service/gpu_timing.h
@@ -5,6 +5,8 @@
 #ifndef GPU_COMMAND_BUFFER_SERVICE_GPU_TIMING_H_
 #define GPU_COMMAND_BUFFER_SERVICE_GPU_TIMING_H_
 
+#include <vector>
+
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "gpu/gpu_export.h"
@@ -51,19 +53,24 @@ class GPU_EXPORT GPUTiming {
     kTimerTypeDisjoint  // EXT_disjoint_timer_query
   };
 
-  GPUTiming();
+  GPUTiming(gfx::GLContext* gl_context = NULL);

[Daniele Castagna, 2015/02/23 22:21:19]

nit: explicit

Why do you pass the context here? Are you passing an actual context to the
constructor anywhere?

nullptr is preferred according to https://chromium-cpp.appspot.com/

   virtual ~GPUTiming();
 
-  bool Initialize(gfx::GLContext* context);
+  void Initialize(gfx::GLContext* gl_context);
   bool IsAvailable();
 
+  int CreateDisjointContextID();
+  bool ReleaseDisjointContextID(int disjoint_context_id);
+  int GetDisjointContextIDCount() const;
+
   // CheckAndResetTimerErrors has to be called before reading timestamps
   // from GPUTimers instances and after making sure all the timers
   // were available.
   // If the returned value is false, all the previous timers should be
   // discarded.
-  bool CheckAndResetTimerErrors();
-
+  bool CheckAndResetTimerErrors(int disjoint_context_id);

[Daniele Castagna, 2015/02/23 22:21:19]

Can you leave the previous method as well, so that this api can be used without
creating a disjoint_context_id.

+  
+  TimerType GetTimerType() const { return timer_type_; }
   const char* GetTimerTypeName() const;
 
   // Returns the offset between the current gpu time and the cpu time.
@@ -71,14 +78,24 @@ class GPU_EXPORT GPUTiming {
   void InvalidateTimerOffset();
 
   void SetCpuTimeForTesting(const base::Callback<int64(void)>& cpu_time);
-  void SetOffsetForTesting(int64 offset, bool cache_it);
-  void SetTimerTypeForTesting(TimerType type);
 
  private:
   TimerType timer_type_ = kTimerTypeInvalid;
   int64 offset_ = 0;  // offset cache when timer_type_ == kTimerTypeARB
   bool offset_valid_ = false;
+  bool disjoint_occurred_ = false;
   base::Callback<int64(void)> cpu_time_for_testing_;
+
+  struct DisjointContext {
+    DisjointContext(bool initial_value)
+        : valid_(true),
+          disjoint_value_(initial_value) {
+    }
+    bool valid_;
+    bool disjoint_value_;
+  };
+  std::vector<DisjointContext> disjoint_contexts_;

[Daniele Castagna, 2015/02/23 22:21:19]

You never shrink this vector when a context is released.

+
   friend class GPUTimer;
   DISALLOW_COPY_AND_ASSIGN(GPUTiming);
 };