Remove RuntimeAPIDelegate::GetPreviousVersion.

extensions/browser/api/runtime/runtime_api_delegate.h

 // 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.
 
 #ifndef EXTENSIONS_BROWSER_API_RUNTIME_RUNTIME_API_DELEGATE_H_
 #define EXTENSIONS_BROWSER_API_RUNTIME_RUNTIME_API_DELEGATE_H_
 
 #include "base/callback.h"
 #include "base/version.h"
 
@@ skipping 33 matching lines @@
 
   // The callback given to RequestUpdateCheck.
   typedef base::Callback<void(const UpdateCheckResult&)> UpdateCheckCallback;
 
   // Registers an UpdateObserver on behalf of the runtime API.
   virtual void AddUpdateObserver(UpdateObserver* observer) = 0;
 
   // Unregisters an UpdateObserver on behalf of the runtime API.
   virtual void RemoveUpdateObserver(UpdateObserver* observer) = 0;
 
-  // Determines an extension's previously installed version if applicable.
-  virtual base::Version GetPreviousExtensionVersion(
-      const Extension* extension) = 0;
-
   // Reloads an extension.
   virtual void ReloadExtension(const std::string& extension_id) = 0;
 
   // Requests an extensions update update check. Returns |false| if updates
   // are disabled. Otherwise |callback| is called with the result of the
   // update check.
   virtual bool CheckForUpdates(const std::string& extension_id,
                                const UpdateCheckCallback& callback) = 0;
 
   // Navigates the browser to a URL on behalf of the runtime API.
@@ skipping 10 matching lines @@
   // Open |extension|'s options page, if it has one. Returns true if an
   // options page was opened, false otherwise. See the docs of the
   // chrome.runtime.openOptionsPage function for the gritty details.
   virtual bool OpenOptionsPage(const Extension* extension,
                                content::BrowserContext* browser_context);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_RUNTIME_RUNTIME_API_DELEGATE_H_