Use mac browser action overflow asset on all platforms

Use mac browser action overflow asset on all platforms

Hot on the heels of r175591, we're now using the centered
asset everywhere.

This moves the mac asset over to common, removes the one in the
root directory (which was used by gtk), and updates the grd file.

BUG=168897
TEST=look at browser actions overflow asset, it's vertically centered.
on all platforms.
TBR=sail

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=175612

[Nico, 2013-01-08 23:47:56]

erg: This new asset is 2px wider than the old one, but
c/b/ui/gtk/custom_button.cc looks like it'll adapt to the new width
automatically, so I guess this should be fine?

[Elliot Glaysher, 2013-01-08 23:50:18]

On 2013/01/08 23:47:56, Nico wrote:
> erg: This new asset is 2px wider than the old one, but
> c/b/ui/gtk/custom_button.cc looks like it'll adapt to the new width
> automatically, so I guess this should be fine?

theoretically. as long as you aren't touching the height, this should be ok.
lgtm.