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

chrome/browser/plugin_installer_observer.h

-// 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.
-
-#ifndef CHROME_BROWSER_PLUGIN_INSTALLER_OBSERVER_H_
-#define CHROME_BROWSER_PLUGIN_INSTALLER_OBSERVER_H_
-
-#include <string>
-
-class PluginInstaller;
-
-class PluginInstallerObserver {
- public:
-  explicit PluginInstallerObserver(PluginInstaller* installer);
-  virtual ~PluginInstallerObserver();
-
- protected:
-  PluginInstaller* installer() const { return installer_; }
-
- private:
-  friend class PluginInstaller;
-
-  virtual void DownloadStarted();
-  virtual void DownloadFinished();
-  virtual void DownloadError(const std::string& message);
-  virtual void DownloadCancelled();
-
-  // Weak pointer; Owned by PluginFinder, which is a singleton.
-  PluginInstaller* installer_;
-};
-
-// A WeakPluginInstallerObserver is like a weak pointer to the installer, in the
-// sense that if only weak observers are left, we don't need to show
-// installation UI anymore.
-class WeakPluginInstallerObserver : public PluginInstallerObserver {
- public:
-  explicit WeakPluginInstallerObserver(PluginInstaller* installer);
-  virtual ~WeakPluginInstallerObserver();
-
- private:
-  friend class PluginInstaller;
-
-  virtual void OnlyWeakObserversLeft();
-};
-
-#endif  // CHROME_BROWSER_PLUGIN_INSTALLER_OBSERVER_H_