chromeos: Avoid useless warning on lookup of display mode 0.

chromeos/display/output_configurator.cc

Index: chromeos/display/output_configurator.cc
diff --git a/chromeos/display/output_configurator.cc b/chromeos/display/output_configurator.cc
index 4e8f2a861c180f430b144d131a2c32a3c635ee09..78cb31869d4bca60403cbc4c4909b547e95d431a 100644
--- a/chromeos/display/output_configurator.cc
+++ b/chromeos/display/output_configurator.cc
@@ -169,6 +169,9 @@ bool OutputConfigurator::TestApi::TriggerConfigureTimeout() {
 const OutputConfigurator::ModeInfo* OutputConfigurator::GetModeInfo(
     const OutputSnapshot& output,
     RRMode mode) {
+  if (mode == None)
+    return NULL;
+
   std::map<RRMode, ModeInfo>::const_iterator it = output.mode_infos.find(mode);
   if (it == output.mode_infos.end()) {
     LOG(WARNING) << "Unable to find info about mode " << mode