mash: Move TrayTracing to //ash/common/system/chromeos

ash/common/system/tray/wm_system_tray_notifier.cc

Index: ash/common/system/tray/wm_system_tray_notifier.cc
diff --git a/ash/common/system/tray/wm_system_tray_notifier.cc b/ash/common/system/tray/wm_system_tray_notifier.cc
index c790656a490c7def795ca6435db063b3db8f2203..ef9690ca2446117bb8172b7a8554ab73db41d463 100644
--- a/ash/common/system/tray/wm_system_tray_notifier.cc
+++ b/ash/common/system/tray/wm_system_tray_notifier.cc
@@ -11,6 +11,7 @@
 #include "ash/common/system/update/update_observer.h"
 
 #if defined(OS_CHROMEOS)
+#include "ash/common/system/chromeos/tray_tracing.h"
 #include "ash/common/system/chromeos/virtual_keyboard/virtual_keyboard_observer.h"
 #endif
 
@@ -147,6 +148,19 @@ void WmSystemTrayNotifier::NotifyUpdateRecommended(const UpdateInfo& info) {
 
 #if defined(OS_CHROMEOS)
 
+void WmSystemTrayNotifier::AddTracingObserver(TracingObserver* observer) {
+  tracing_observers_.AddObserver(observer);
+}
+
+void WmSystemTrayNotifier::RemoveTracingObserver(TracingObserver* observer) {
+  tracing_observers_.RemoveObserver(observer);
+}
+
+void WmSystemTrayNotifier::NotifyTracingModeChanged(bool value) {
+  FOR_EACH_OBSERVER(TracingObserver, tracing_observers_,
+                    OnTracingModeChanged(value));
+}
+
 void WmSystemTrayNotifier::AddVirtualKeyboardObserver(
     VirtualKeyboardObserver* observer) {
   virtual_keyboard_observers_.AddObserver(observer);