Skeleton for app_list on OSX, and refactoring for enable_app_list=1 on OS=="mac".

ui/app_list/cocoa/app_list_view_window.mm

+// Copyright 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.
+
+#import "ui/app_list/cocoa/app_list_view_window.h"
+
+@implementation AppListViewWindow;
+
+- (id)initAsBubble {
+  const int kWindowWidth = 200;
+  const int kWindowHeight = 200;
+  NSRect frame = NSMakeRect(0, 0, kWindowWidth, kWindowHeight);
+  if ((self = [super initWithContentRect:frame
+                               styleMask:NSBorderlessWindowMask
+                                 backing:NSBackingStoreBuffered
+                                   defer:NO])) {
+    [self setReleasedWhenClosed:NO];
+    [self setBackgroundColor:[NSColor grayColor]];
+  }
+
+  return self;
+}
+
+@end