Speculative revert 175230. I suspect that dependency on propsys.dll makes chrome.dll unloadable on …

Speculative revert 175230. I suspect that dependency on propsys.dll makes chrome.dll unloadable on XP SP3 breaking NACL and chrome frame tests.

> [Fixit-Dec-2012] Also add dual_mode to Start Menu shortcuts in MigrateChromiumShortcuts.
> 
> Restructured this code quite a bit to use the new shortcut magic.
> 
> Added tests which turned out to expose edge cases that I think weren't covered by the previous implementation (i.e. would potentially update shortcuts when unecessary -- flashing the desktop in the process -- or not do it when necessary).
> 
> BUG=142980
> TEST=Pin Desktop shortcut to Start Screen or pin chrome.exe directly to the start screen via context menu.
> Notice that there are now multiple shortcuts of Chrome (non-tiled; 1 for each "Pin to Start" action; upon launching Chrome those should all be merged down to one Chrome tile shortcut (not on the file system, but visually on the Start Screen itself).
> Note: if you do try this; there is an intentional 15s delay before the migration kicks in to avoid delaying Chrome startup; so be patient, it will work ;)!
> 
> Review URL: https://chromiumcodereview.appspot.com/11712003

TBR=gab@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=175244