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

base/win/registry.h

Index: base/win/registry.h
diff --git a/base/win/registry.h b/base/win/registry.h
index 2ef759bf4cba5724b0caa2c1ab77f60f76f1aebc..e3f37602863034ff6a045ea5f84877879346c303 100644
--- a/base/win/registry.h
+++ b/base/win/registry.h
@@ -132,8 +132,20 @@ class BASE_EXPORT RegKey {
   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);
 };