Added Destroy() functions for GPUTimer and GPUTracer/GPUTrace.

ui/gl/gpu_timing.cc

 // Copyright (c) 2015 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 "ui/gl/gpu_timing.h"
 
 #include "base/time/time.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_version_info.h"
@@ skipping 26 matching lines @@
     GLint disjoint_value = 0;
     glGetIntegerv(GL_GPU_DISJOINT_EXT, &disjoint_value);
     if (disjoint_value) {
       disjoint_counter_++;
     }
   }
   return disjoint_counter_;
 }
 
 GPUTimer::~GPUTimer() {
-  glDeleteQueries(2, queries_);
+  // Destroy() must be called before the destructor.
+  DCHECK(queries_[0] == 0);
+  DCHECK(queries_[1] == 0);
+}
+
+void GPUTimer::Destroy(bool have_context) {
+  if (have_context) {
+    glDeleteQueries(2, queries_);
+  }
+  memset(queries_, 0, sizeof(queries_));
 }
 
 void GPUTimer::Start() {
   switch (gpu_timing_client_->gpu_timing_->timer_type_) {
     case GPUTiming::kTimerTypeARB:
     case GPUTiming::kTimerTypeDisjoint:
       // GL_TIMESTAMP and GL_TIMESTAMP_EXT both have the same value.
       glQueryCounter(queries_[0], GL_TIMESTAMP);
       break;
     case GPUTiming::kTimerTypeEXT:
@@ skipping 156 matching lines @@
 
 void GPUTimingClient::SetCpuTimeForTesting(
     const base::Callback<int64(void)>& cpu_time) {
   cpu_time_for_testing_ = cpu_time;
 }
 
 GPUTimingClient::~GPUTimingClient() {
 }
 
 }  // namespace gfx