Move ZoomObserver, ZoomController and ZoomEventManager to components/.

chrome/browser/ui/zoom/zoom_event_manager.cc

-// Copyright 2014 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/ui/zoom/zoom_event_manager.h"
-
-#include "content/public/browser/browser_context.h"
-
-namespace {
-static const char kBrowserZoomEventManager[] = "browser_zoom_event_manager";
-}
-
-ZoomEventManager* ZoomEventManager::GetForBrowserContext(
-    content::BrowserContext* context) {
-  if (!context->GetUserData(kBrowserZoomEventManager))
-    context->SetUserData(kBrowserZoomEventManager, new ZoomEventManager);
-  return static_cast<ZoomEventManager*>(
-      context->GetUserData(kBrowserZoomEventManager));
-}
-
-ZoomEventManager::ZoomEventManager() : weak_ptr_factory_(this) {
-}
-
-ZoomEventManager::~ZoomEventManager() {}
-
-void ZoomEventManager::OnZoomLevelChanged(
-    const content::HostZoomMap::ZoomLevelChange& change) {
-  zoom_level_changed_callbacks_.Notify(change);
-}
-
-scoped_ptr<content::HostZoomMap::Subscription>
-ZoomEventManager::AddZoomLevelChangedCallback(
-    const content::HostZoomMap::ZoomLevelChangedCallback& callback) {
-  return zoom_level_changed_callbacks_.Add(callback);
-}