stub impl of linux,mac icon loader/manager

chrome/browser/icon_manager_linux.cc

Index: chrome/browser/icon_manager_linux.cc
===================================================================
--- chrome/browser/icon_manager_linux.cc	(revision 0)
+++ chrome/browser/icon_manager_linux.cc	(revision 0)
@@ -0,0 +1,12 @@
+// Copyright (c) 2009 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 "chrome/browser/icon_manager.h"
+
+#include "base/file_path.h"
+
+IconGroupID IconManager::GetGroupIDFromFilepath(const FilePath& filepath) {
+  NOTIMPLEMENTED();
+  return std::string();
+}