Add systemInfo.cpu.onUpdated event implementation.

chrome/browser/extensions/system_info_event_router.h

Index: chrome/browser/extensions/system_info_event_router.h
diff --git a/chrome/browser/extensions/system_info_event_router.h b/chrome/browser/extensions/system_info_event_router.h
index a6e22a930f9bf03f91c77a55c10d241b41496f85..f239b1a34806353f095b8903f09314afb72ff5b6 100644
--- a/chrome/browser/extensions/system_info_event_router.h
+++ b/chrome/browser/extensions/system_info_event_router.h
@@ -13,6 +13,12 @@
 
 namespace extensions {
 
+namespace api {
+namespace experimental_system_info_cpu {
+struct CpuUpdateInfo;
+}
+}
+
 // Event router for systemInfo API. It is a singleton instance shared by
 // multiple profiles.
 // TODO(hongbo): It should derive from SystemMonitor::DevicesChangedObserver.
@@ -46,11 +52,15 @@ class SystemInfoEventRouter {
   SystemInfoEventRouter();
   virtual ~SystemInfoEventRouter();
 
-  // Called on the UI thread to dispatch the systemInfo event to all extension
+  // Called from any thread to dispatch the systemInfo event to all extension
   // processes cross multiple profiles.
   void DispatchEvent(const std::string& event_name,
       scoped_ptr<base::ListValue> args);
 
+  // The callback for CPU sampling cycle. Can be called from any thread.
+  void OnNextCpuSampling(
+      scoped_ptr<api::experimental_system_info_cpu::CpuUpdateInfo> info);
+
   // Used to record the event names being watched.
   std::multiset<std::string> watching_event_set_;