Add WOW64 support to DeleteKey.  Add DeleteEmptyKey to mimic SHDeleteEmptyKey.  Add lots of WOW64 tests.  Add a DeleteKey and a CreateKey test.

These additions are needed to support Win64 installer logic.

BUG=338706,348626
TEST=base_unittests --gtest_filter=Registry* on XP (x86), Vista (x86/x64), Win7 (x86/x64).
TEST=installer_util_unittests
R=cpu@chromium.org, grt@chromium.org

Review URL: https://codereview.chromium.org/275103012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272213 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed