size_t fixes for building on win x64

Fixes C4267 warnings, and errors regarding passing size_t* when they chould be unsigned int *.

winrt_utils:
WindowsCreateString takes a UINT32 as size. Truncation would mean
shorter than expected string, but presumably not a severe problem
in this case.

file_picker:
The interface uses unsigned int, not size_t, so change implementation and callers to unsigned int.


R=cpu@chromium.org
BUG=166496


Review URL: https://chromiumcodereview.appspot.com/11884021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@176854 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed