Modify overinstall flow for Google Cloud Printer to uninstall any previous version before installing. The new flow retrieves the location of the uninstall exe from the registry and copies it to a temp location.  It marks the temp uninstaller for deletion on reboot and then launches it and waits for it to exit. Installation will proceed if there was no previous install or the uninstall succeeded.
Modify overinstall flow for Google Cloud Printer to uninstall any previous version before installing.
The new flow retrieves the location of the uninstall exe from the registry and copies it to a temp location.  It marks the temp uninstaller for deletion on reboot and then launches it and waits for it to exit.
Installation will proceed if there was no previous install or the uninstall succeeded.

BUG=123091
TEST=Verify 123091


Review URL: http://codereview.chromium.org/10054040

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@132037 0039d316-1c4b-4281-b951-d872f2087c98

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