Add WOW64 support and DeleteEmptyKey to base::win::registry.

base/win/registry.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 BASE_WIN_REGISTRY_H_
 #define BASE_WIN_REGISTRY_H_
 
 #include <windows.h>
 #include <string>
 #include <vector>
@@ skipping 114 matching lines @@
 
   // Will automatically be called by destructor if not manually called
   // beforehand.  Returns true if it was watching, false otherwise.
   LONG StopWatching();
 
   inline bool IsWatching() const { return watch_event_ != 0; }
   HANDLE watch_event() const { return watch_event_; }
   HKEY Handle() const { return key_; }
 
  private:
+  // Wrapper function for RegDeleteKeyEx which is not supported on all

[grt (UTC plus 2), 2014/05/17 12:54:33]

Please make the comments descriptive as per the style guide
(http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Function_Comments).
For example:

  // Calls RegDeleteKeyEx on supported platforms. Otherwise, attempts to delete
the key via RegDeleteKey.

[Will Harris, 2014/05/19 21:49:03]

Done.

+  // platforms.  Behaves like RegDeleteKeyEx.
+  static LONG RegDeleteKeyExWrapper(HKEY hKey,
+                                    const wchar_t* lpSubKey,
+                                    REGSAM samDesired,
+                                    DWORD Reserved);
+
+  // Internal function to perform a recursive registry key delete.

[grt (UTC plus 2), 2014/05/17 12:54:33]

suggestion:
  // Recursively deletes a key and all of its subkeys.

[Will Harris, 2014/05/19 21:49:03]

Done.

+  static LONG RegDelRecurse(HKEY root_key,
+                            std::wstring const& name,

[grt (UTC plus 2), 2014/05/17 12:54:33]

const std::wstring&

[Will Harris, 2014/05/19 21:49:03]

Done.

+                            REGSAM access);
   HKEY key_;  // The registry key being iterated.
   HANDLE watch_event_;
+  REGSAM wow64access_;
 
   DISALLOW_COPY_AND_ASSIGN(RegKey);
 };
 
 // Iterates the entries found in a particular folder on the registry.
 class BASE_EXPORT RegistryValueIterator {
  public:
   RegistryValueIterator(HKEY root_key, const wchar_t* folder_key);
 
   ~RegistryValueIterator();
@@ skipping 63 matching lines @@
 
   wchar_t name_[MAX_PATH];
 
   DISALLOW_COPY_AND_ASSIGN(RegistryKeyIterator);
 };
 
 }  // namespace win
 }  // namespace base
 
 #endif  // BASE_WIN_REGISTRY_H_