Allow relative paths to external extension files for some providers, error out for others.

chrome/browser/extensions/external_pref_extension_loader.h

 // Copyright (c) 2011 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_EXTENSIONS_EXTERNAL_PREF_EXTENSION_LOADER_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTERNAL_PREF_EXTENSION_LOADER_H_
 #pragma once
 
 #include "chrome/browser/extensions/external_extension_loader.h"
 
 #include <string>
 
 #include "base/scoped_ptr.h"
 #include "base/values.h"
 
 // A specialization of the ExternalExtensionLoader that uses a json file to
 // look up which external extensions are registered.
 // Instances of this class are expected to be created and destroyed on the UI
 // thread and they are expecting public method calls from the UI thread.
 class ExternalPrefExtensionLoader : public ExternalExtensionLoader {
  public:
-  ExternalPrefExtensionLoader();
+  // |base_path_key| is the directory containing the external_extensions.json
+  // file.  Relative file paths to extension files are resolved relative
+  // to this path.
+  explicit ExternalPrefExtensionLoader(int base_path_key);
+
+  virtual const FilePath GetBaseCrxFilePath();
 
  protected:
   virtual void StartLoading();
 
  private:
   friend class base::RefCountedThreadSafe<ExternalExtensionLoader>;
 
   virtual ~ExternalPrefExtensionLoader() {}
 
   void LoadOnFileThread();
 
+  int base_path_key_;
+  FilePath base_path_;
+
   DISALLOW_COPY_AND_ASSIGN(ExternalPrefExtensionLoader);
 };
 
 // A simplified version of ExternalPrefExtensionLoader that loads the dictionary
 // from json data specified in a string.
 class ExternalTestingExtensionLoader : public ExternalExtensionLoader {
  public:
-  explicit ExternalTestingExtensionLoader(const std::string& json_data);
+  ExternalTestingExtensionLoader(
+      const std::string& json_data,
+      const FilePath& fake_base_path);
+
+  virtual const FilePath GetBaseCrxFilePath();
 
  protected:
   virtual void StartLoading();
 
  private:
   friend class base::RefCountedThreadSafe<ExternalExtensionLoader>;
 
   virtual ~ExternalTestingExtensionLoader() {}
 
+  FilePath fake_base_path_;
   scoped_ptr<DictionaryValue> testing_prefs_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalTestingExtensionLoader);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTERNAL_PREF_EXTENSION_LOADER_H_