Fix 4027057: Improve resolution of RecentApps thumbnail images.

This fix ensures captured thumbnails in portrait mode have the
same resolution as those in landscape by fixing the horizontal
resolution and vertical resolution of the target image.

The returned image is now always the same size and matches
the landscape screen exactly. In portrait mode, it grabs
the upper portion of the screen based on the vertical dimension
of the target image.

Change-Id: I203c39843f2f21ca28f6ef0dffec308ce5cb39fb