Registry overriding doesn't seem to work across multiple processes prior to Win8, instead simply ha…

chrome/browser/importer/ie_importer_test_registry_overrider_win.h

 // Copyright (c) 2013 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_IMPORTER_IE_IMPORTER_TEST_REGISTRY_OVERRIDER_WIN_H_
 #define CHROME_BROWSER_IMPORTER_IE_IMPORTER_TEST_REGISTRY_OVERRIDER_WIN_H_
 
 #include "base/basictypes.h"
-#include "base/lazy_instance.h"
 #include "base/string16.h"
-#include "base/synchronization/lock.h"
 
-// A helper class to override HKEY_CURRENT_USER to point to a test key from this
-// process' point of view. Uses a random guid as a subkey for the override in
-// order for multiple tests to be able to use this functionality in parallel.
-// Also provides functionality (via an environment variable) to let child
-// processes check whether they should also override. This class is thread-safe.
-// Always unsets any existing override upon being deleted.
+// A helper class to let tests generate a random registry key to be used in
+// HKEY_CURRENT_USER in tests. After the key has been generated via
+// SetTestRegistryOverride(), consumers in this process (or in any child
+// processes created after the key has been generated) can obtain the key via
+// GetTestRegistryOverride(). IEImporterTestRegistryOverrider will delete the
+// temporary key upon being deleted itself.
 class IEImporterTestRegistryOverrider {
  public:
   IEImporterTestRegistryOverrider();
 
   // Unsets any existing registry override and deletes the temporary registry
   // key if |override_initiated_|.
   ~IEImporterTestRegistryOverrider();
 
-  // Calls StartRegistryOverride() and sets an environment variable so that
-  // future calls to StartRegistryOverrideIfNeeded() from child processes also
-  // result in an overriden HKEY_CURRENT_USER hive. This method should only be
-  // called once across all processes.
-  // Returns false on unexpected failure.
-  bool SetRegistryOverride();
+  // Sets an environment variable so that future calls to
+  // GetTestRegistryOverride() from this process and child processes result in
+  // the test key being returned to the caller. This method should only be
+  // called once. Returns false on failure to set the environment variable.
+  // NOTE: This method does not create the key itself.
+  bool SetTestRegistryOverride();
 
-  // Calls StartRegistryOverride() if the environment was set by a parent
-  // process via SetRegistryOverride().
-  // Returns false on unexpected failure.
-  bool StartRegistryOverrideIfNeeded();
+  // Returns a test key if one was chosen and set by a call to
+  // SetTestRegistryOverride(); returns the empty string if none.
+  static base::string16 GetTestRegistryOverride();
 
  private:
-  // Overrides HKCU to point to a test key (ending with |subkey|) from this
-  // process' point of view. Re-applies the override without taking ownership if
-  // |override_active_in_process_|.
-  // Returns false on unexpected failure.
-  bool StartRegistryOverride(const base::string16& subkey);
-
-  // Reads the environment variable set by SetRegistryOverride into |subkey| if
-  // it exists. Returns true if the variable was successfully read.
-  bool GetSubKeyFromEnvironment(base::string16* subkey);
-
-  // Whether this object started an override for the current process (and thus
-  // will be responsible for unsetting it when done).
-  bool override_performed_;
-
   // Whether this object is the one that initiated the override via
-  // SetRegistryOverride() (and thus will be the one responsible for deleting
-  // the temporary key when done).
+  // SetTestRegistryOverride() (and thus will be the one responsible for
+  // deleting the temporary key when done).
   bool override_initiated_;
 
-  // Whether a registry override was initiated in the current process.
-  static bool override_active_in_process_;
-
-  // This lock should be held before accessing this class' static data and any
-  // of its objects' members.
-  static base::LazyInstance<base::Lock>::Leaky lock_;
-
   DISALLOW_COPY_AND_ASSIGN(IEImporterTestRegistryOverrider);
 };
 
 #endif  // CHROME_BROWSER_IMPORTER_IE_IMPORTER_TEST_REGISTRY_OVERRIDER_WIN_H_