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>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/stl_util.h"
 
 namespace base {
 namespace win {
 
 // Utility class to read, write and manipulate the Windows Registry.
 // Registry vocabulary primer: a "key" is like a folder, in which there
 // are "values", which are <name, data> pairs, with an associated data type.
 //
 // Note:
 // ReadValue family of functions guarantee that the return arguments
 // are not touched in case of failure.
 class BASE_EXPORT RegKey {
  public:
   RegKey();
   explicit RegKey(HKEY key);

[grt (UTC plus 2), 2014/05/20 17:46:56]

please remove this constructor, the Set() method, and the Take method as per my
previous CR comment.

[Will Harris, 2014/05/20 19:22:40]

http://crbug.com/375400 raised, will be done in a subsequent CL as this changes
some caller behavior.

   RegKey(HKEY rootkey, const wchar_t* subkey, REGSAM access);
   ~RegKey();
 
   LONG Create(HKEY rootkey, const wchar_t* subkey, REGSAM access);
 
   LONG CreateWithDisposition(HKEY rootkey, const wchar_t* subkey,
                              DWORD* disposition, REGSAM access);
 
   // Creates a subkey or open it if it already exists.
   LONG CreateKey(const wchar_t* name, REGSAM access);
@@ skipping 24 matching lines @@
   // Determine the nth value's name.
   LONG GetValueNameAt(int index, std::wstring* name) const;
 
   // True while the key is valid.
   bool Valid() const { return key_ != NULL; }
 
   // Kill a key and everything that live below it; please be careful when using
   // it.
   LONG DeleteKey(const wchar_t* name);
 
+  // Deletes an empty subkey.  If the subkey has subkeys or values then this
+  // will fail.
+  LONG DeleteEmptyKey(const wchar_t* name);
+
   // Deletes a single value within the key.
   LONG DeleteValue(const wchar_t* name);
 
   // Getters:
 
   // Returns an int32 value. If |name| is NULL or empty, returns the default
   // value, if any.
   LONG ReadValueDW(const wchar_t* name, DWORD* out_value) const;
 
   // Returns an int64 value. If |name| is NULL or empty, returns the default
@@ skipping 41 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:
+  // Calls RegDeleteKeyEx on supported platforms, alternatively falls back to
+  // RegDeleteKey.
+  static LONG RegDeleteKeyExWrapper(HKEY hKey,
+                                    const wchar_t* lpSubKey,
+                                    REGSAM samDesired,
+                                    DWORD Reserved);
+
+  // Recursively deletes a key and all of its subkeys.
+  static LONG RegDelRecurse(HKEY root_key,
+                            const std::wstring& name,
+                            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_