Remove FOR_EACH_OBSERVER from arc/ since it's being deprecated

components/arc/instance_holder.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_ARC_INSTANCE_HOLDER_H_
 #define COMPONENTS_ARC_INSTANCE_HOLDER_H_
 
 #include <string>
 #include <utility>
 
@@ skipping 81 matching lines @@
     DCHECK(instance == nullptr || instance_ == nullptr);
 
     // Note: This can be called with nullptr even if |instance_| is still
     // nullptr for just in case clean up purpose. No-op in such a case.
     if (instance == instance_)
       return;
 
     instance_ = instance;
     version_ = version;
     if (instance_) {
-      FOR_EACH_OBSERVER(Observer, observer_list_, OnInstanceReady());
+      for (auto& observer : observer_list_)
+        observer.OnInstanceReady();
     } else {
-      FOR_EACH_OBSERVER(Observer, observer_list_, OnInstanceClosed());
+      for (auto& observer : observer_list_)
+        observer.OnInstanceClosed();
     }
   }
 
  private:
   // This class does not have ownership. The pointers should be managed by the
   // callee.
   T* instance_ = nullptr;
   uint32_t version_ = 0;
 
   base::ThreadChecker thread_checker_;
   base::ObserverList<Observer> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(InstanceHolder<T>);
 };
 
 }  // namespace arc
 
 #endif  // COMPONENTS_ARC_INSTANCE_HOLDER_H_