Reduce internal Flush() in GL resource glGen/Delete APIs.

gpu/command_buffer/client/cmd_buffer_helper.cc

Index: gpu/command_buffer/client/cmd_buffer_helper.cc
diff --git a/gpu/command_buffer/client/cmd_buffer_helper.cc b/gpu/command_buffer/client/cmd_buffer_helper.cc
index 693063dc04bbade3128b2969266b7dd0ee8dcb22..f7a0a18a75acb756ae0d138c53b0e306a666e846 100644
--- a/gpu/command_buffer/client/cmd_buffer_helper.cc
+++ b/gpu/command_buffer/client/cmd_buffer_helper.cc
@@ -156,6 +156,7 @@ bool CommandBufferHelper::FlushSync() {
   last_flush_time_ = clock();
   last_put_sent_ = put_;
   CommandBuffer::State state = command_buffer_->FlushSync(put_, get_offset());
+  ++flush_generation_;
   CalcImmediateEntries(0);
   return state.error == error::kNoError;
 }
@@ -169,6 +170,7 @@ void CommandBufferHelper::Flush() {
     last_flush_time_ = clock();
     last_put_sent_ = put_;
     command_buffer_->Flush(put_);
+    ++flush_generation_;
     CalcImmediateEntries(0);
   }
 }