Add OnDisplayMetricsChanged in DisplayObserver.

chrome/browser/ui/webui/options/chromeos/display_overscan_handler.cc

Index: chrome/browser/ui/webui/options/chromeos/display_overscan_handler.cc
diff --git a/chrome/browser/ui/webui/options/chromeos/display_overscan_handler.cc b/chrome/browser/ui/webui/options/chromeos/display_overscan_handler.cc
index c176b0b0ca89cca60a61423176d420d807344d72..d7d5d929f9c31fc5ff6273ae039f93b1fed067cd 100644
--- a/chrome/browser/ui/webui/options/chromeos/display_overscan_handler.cc
+++ b/chrome/browser/ui/webui/options/chromeos/display_overscan_handler.cc
@@ -81,10 +81,6 @@ void DisplayOverscanHandler::RegisterMessages() {
                  base::Unretained(this)));
 }
 
-void DisplayOverscanHandler::OnDisplayBoundsChanged(
-    const gfx::Display& display) {
-}
-
 void DisplayOverscanHandler::OnDisplayAdded(const gfx::Display& new_display) {
   web_ui()->CallJavascriptFunction(
       "options.DisplayOverscan.onOverscanCanceled");
@@ -95,6 +91,10 @@ void DisplayOverscanHandler::OnDisplayRemoved(const gfx::Display& old_display) {
       "options.DisplayOverscan.onOverscanCanceled");
 }
 
+void DisplayOverscanHandler::OnDisplayMetricsChanged(const gfx::Display&,
+                                                     uint32_t) {
+}
+
 void DisplayOverscanHandler::HandleStart(const base::ListValue* args) {
   int64 display_id = gfx::Display::kInvalidDisplayID;
   std::string id_value;