Move chrome/browser/plugin_* to chrome/browser/plugins/

chrome/browser/plugin_installer_observer.cc

-// Copyright (c) 2012 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/plugin_installer_observer.h"
-
-#include "chrome/browser/plugin_installer.h"
-
-PluginInstallerObserver::PluginInstallerObserver(PluginInstaller* installer)
-    : installer_(installer) {
-  installer->AddObserver(this);
-}
-
-PluginInstallerObserver::~PluginInstallerObserver() {
-  installer_->RemoveObserver(this);
-}
-
-void PluginInstallerObserver::DownloadStarted() {
-}
-
-void PluginInstallerObserver::DownloadFinished() {
-}
-
-void PluginInstallerObserver::DownloadError(const std::string& message) {
-}
-
-void PluginInstallerObserver::DownloadCancelled() {
-}
-
-WeakPluginInstallerObserver::WeakPluginInstallerObserver(
-    PluginInstaller* installer) : PluginInstallerObserver(installer) {
-  installer->AddWeakObserver(this);
-}
-
-WeakPluginInstallerObserver::~WeakPluginInstallerObserver() {
-  installer()->RemoveWeakObserver(this);
-}
-
-void WeakPluginInstallerObserver::OnlyWeakObserversLeft() {
-}