Add clean-up code to SetAppIdForWindow()....

Add clean-up code to SetAppIdForWindow().
This is a follow-up change for r21596.
It seems this change forgot calling pps->Release() and PropVariantClear(&pv). (InitPropVariantFromString() calls SHStrDupW() to create a copy of its input string, so we have to call PropVariantClear() and delete it.)
To avoid an object leak and a memory leak, this change uses ScopedComPtr<IPropertyStore> to call Release() in its destructor and call PropVariantClear() to clean-up PROPVARIANT.
(My JumpList class uses a class which encapsulates PROPVARIANT. We should move the class to win_util?)

BUG=none
TEST=none (Run Chromium on purify running on Windows 7.)

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=21830

[brg, 2009-07-27 16:40:52]

LGTM.

Good catch.