Force time elapsed queries on certain drivers.

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/macros.h"
 #include "base/time/time.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
@@ skipping 299 matching lines @@
  private:
   ~TimeStampTimerQuery() override {}
   uint32_t gl_query_id_ = 0;
   scoped_refptr<QueryResult> query_result_;
 };
 
 GPUTimingImpl::GPUTimingImpl(GLContextReal* context) {
   DCHECK(context);
   const GLVersionInfo* version_info = context->GetVersionInfo();
   DCHECK(version_info);
-  if (version_info->is_es3 &&  // glGetInteger64v is supported under ES3.
-    context->HasExtension("GL_EXT_disjoint_timer_query")) {
+  if (context->HasExtension("GL_EXT_disjoint_timer_query")) {
     timer_type_ = GPUTiming::kTimerTypeDisjoint;
+    if (!version_info->is_es3) {
+      // Due to a bug in the specification, glGetInteger64v is only supported
+      // under ES3. Since it is only used for timestamps, we workaround this by
+      // emulating timestamps on ES2 so WebGL 1.0 will still have access to the
+      // extension
+      force_time_elapsed_query_ = true;
+      timestamp_bit_count_gl_ = 0;
+    }
   } else if (context->HasExtension("GL_ARB_timer_query")) {
     timer_type_ = GPUTiming::kTimerTypeARB;
   } else if (context->HasExtension("GL_EXT_timer_query")) {
     timer_type_ = GPUTiming::kTimerTypeEXT;
     force_time_elapsed_query_ = true;
     timestamp_bit_count_gl_ = 0;
   }
 }
 
 GPUTimingImpl::~GPUTimingImpl() {
@@ skipping 319 matching lines @@
 
 void GPUTimingClient::ForceTimeElapsedQuery() {
   DCHECK(gpu_timing_);
   gpu_timing_->ForceTimeElapsedQuery();
 }
 
 GPUTimingClient::~GPUTimingClient() {
 }
 
 }  // namespace gfx