Add an explicit ObjectWatcher::IsWatching() method

base/win/object_watcher.cc

Index: base/win/object_watcher.cc
diff --git a/base/win/object_watcher.cc b/base/win/object_watcher.cc
index fe209f5e3385ba58b496c56f8f9418c4391e8b57..35609fcf5c39b2aac015c95ff196f410543be162 100644
--- a/base/win/object_watcher.cc
+++ b/base/win/object_watcher.cc
@@ -77,7 +77,11 @@ bool ObjectWatcher::StopWatching() {
   return true;
 }
 
-HANDLE ObjectWatcher::GetWatchedObject() {
+bool ObjectWatcher::IsWatching() const {
+  return object_ != NULL;
+}
+
+HANDLE ObjectWatcher::GetWatchedObject() const {
   return object_;
 }