Unit tests have been created for the GPUTiming.

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 34 matching lines @@
 }
 
 int64 GPUTiming::CalculateTimerOffset(base::Callback<int64(void)> cpu_time) {
   if (!offset_valid_) {
     if (timer_type_ == kTimerTypeDisjoint || timer_type_ == kTimerTypeARB) {
       GLint64 gl_now = 0;
       glGetInteger64v(GL_TIMESTAMP, &gl_now);
       int64 now =
           cpu_time.is_null()
           ? (base::TraceTicks::Now() - base::TraceTicks()).InMicroseconds()
-              : cpu_time.Run();
+          : cpu_time.Run();
       offset_ = now - gl_now / base::Time::kNanosecondsPerMicrosecond;
       offset_valid_ = (timer_type_ == kTimerTypeARB);
     } else {
       // TODO(dyen): figure out how to calculate the offset for EXT_Timer_Query.
       offset_ = 0;
       offset_valid_ = true;
     }
   }
   return offset_;
 }
@@ skipping 178 matching lines @@
   if (gpu_timing_) {
     gpu_timing_->InvalidateTimerOffset();
   }
 }
 
 void GPUTimingClient::SetCpuTimeForTesting(
     const base::Callback<int64(void)>& cpu_time) {
   cpu_time_for_testing_ = cpu_time;
 }
 
+int64 GPUTimingClient::GetCurrentCPUTime() {
+  return cpu_time_for_testing_.is_null()
+         ? (base::TraceTicks::Now() - base::TraceTicks()).InMicroseconds()
+         : cpu_time_for_testing_.Run();
+}
+
 GPUTimingClient::~GPUTimingClient() {
 }
 
 }  // namespace gfx