add "did it run on GPU" check to frame_rate_tests.cc using AutomationProxy tracing feature

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 3fc8f2791be3176da7ca0d2f5288078182ad0022..eb7c6df43d3b747f9b178afe332f1e75b1657e13 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -2050,6 +2050,10 @@ bool GLES2DecoderImpl::Initialize(
     return false;
   }
 
+  // TRACE_EVENT for gpu tests:
+  TRACE_EVENT_INSTANT1("test_gpu", "GLES2DecoderImpl::Initialize", "GLImpl",
+                       static_cast<int>(gfx::GetGLImplementation()));
+
   return true;
 }