Add a gpu.SwapBuffers synthetic delay to PostSubBuffer.

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 a886513fb9bf4a2d4cdb748096cf9f9e39322e34..e324e9b67aaecfe06ad869db385fb1a080264137 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -7547,6 +7547,9 @@ error::Error GLES2DecoderImpl::HandlePixelStorei(
 error::Error GLES2DecoderImpl::HandlePostSubBufferCHROMIUM(
     uint32 immediate_data_size, const cmds::PostSubBufferCHROMIUM& c) {
   TRACE_EVENT0("gpu", "GLES2DecoderImpl::HandlePostSubBufferCHROMIUM");
+  {
+    TRACE_EVENT_SYNTHETIC_DELAY("gpu.PresentingFrame");
+  }
   if (!supports_post_sub_buffer_) {
     LOCAL_SET_GL_ERROR(
         GL_INVALID_OPERATION,
@@ -9055,7 +9058,7 @@ void GLES2DecoderImpl::DoSwapBuffers() {
                "offscreen", is_offscreen,
                "frame", this_frame_number);
   {
-    TRACE_EVENT_SYNTHETIC_DELAY("gpu.SwapBuffers");
+    TRACE_EVENT_SYNTHETIC_DELAY("gpu.PresentingFrame");
   }
 
   bool is_tracing;