content: convert child process notifications to observer usage

content/public/browser/browser_child_process_observer.cc

+// Copyright (c) 2013 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.
+
+#include "content/public/browser/browser_child_process_observer.h"
+
+#include "content/browser/browser_child_process_host_impl.h"
+
+namespace content {
+
+// static
+void BrowserChildProcessObserver::Add(BrowserChildProcessObserver* observer) {
+  BrowserChildProcessHostImpl::AddObserver(observer);
+}
+
+// static
+void BrowserChildProcessObserver::Remove(
+    BrowserChildProcessObserver* observer) {
+  BrowserChildProcessHostImpl::RemoveObserver(observer);
+}
+
+}  // namespace content