WIP: Plumbing input event latency reporting through Mus GPU.

ppapi/proxy/ppapi_command_buffer_proxy.cc

Index: ppapi/proxy/ppapi_command_buffer_proxy.cc
diff --git a/ppapi/proxy/ppapi_command_buffer_proxy.cc b/ppapi/proxy/ppapi_command_buffer_proxy.cc
index dab3a5861be6b3344abe2c6175392fda58e696de..c87961cccc8e3b8e660fdd49133186502298974a 100644
--- a/ppapi/proxy/ppapi_command_buffer_proxy.cc
+++ b/ppapi/proxy/ppapi_command_buffer_proxy.cc
@@ -228,6 +228,9 @@ int32_t PpapiCommandBufferProxy::GetExtraCommandBufferData() const {
   return 0;
 }
 
+void PpapiCommandBufferProxy::AddLatencyInfo(
+    const std::vector<ui::LatencyInfo>& latency_info) {}
+
 void PpapiCommandBufferProxy::SignalQuery(uint32_t query,
                                           const base::Closure& callback) {
   NOTREACHED();