Added disjoint context class which manages disjoints within gpu timing.

gpu/perftests/texture_upload_perftest.cc

 // Copyright 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 <algorithm>
 #include <vector>
 
 #include "base/containers/small_map.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
@@ skipping 104 matching lines @@
     glGenFramebuffersEXT(1, &framebuffer_object_);
     glBindFramebufferEXT(GL_FRAMEBUFFER, framebuffer_object_);
 
     glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                               GL_TEXTURE_2D, color_texture_, 0);
     DCHECK_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
               glCheckFramebufferStatusEXT(GL_FRAMEBUFFER));
 
     glViewport(0, 0, size_.width(), size_.height());
 
-    if (gpu_timing_.Initialize(gl_context_.get())) {
+    gpu_timing_.Initialize(gl_context_.get());
+    if (gpu_timing_.IsAvailable()) {
       LOG(INFO) << "Gpu timing initialized with timer type: "
                 << gpu_timing_.GetTimerTypeName();
-      gpu_timing_.CheckAndResetTimerErrors();

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

This is needed to invalidate the disjoint error that is going to be checked when
crrev.com/944073005 lands.

       gpu_timing_.InvalidateTimerOffset();
     } else {
       LOG(WARNING) << "Can't initialize gpu timing";
     }
     // Prepare a simple program and a vertex buffer that will be
     // used to draw a quad on the offscreen surface.
     vertex_shader_ = LoadShader(GL_VERTEX_SHADER, kVertexShader);
     fragment_shader_ = LoadShader(GL_FRAGMENT_SHADER, kFragmentShader);
     program_object_ = glCreateProgram();
     CHECK_NE(0u, program_object_);
@@ skipping 133 matching lines @@
   }
 
   for (const auto& entry : aggregates) {
     const auto m = entry.second.Divide(kUploadPerfTestRuns);
     m.PrintResult();
   }
 }
 
 }  // namespace
 }  // namespace gpu