[Mac] Do not resize devtools when showing if it is already open.
[Mac] Do not resize devtools when showing if it is already open.

BUG=34494
TEST=Open devtools and resize.  Right-click on the webpage and "Inspect element."  Devtools should not resize to its original size.
Review URL: http://codereview.chromium.org/565040

git-svn-id: http://src.chromium.org/svn/trunk/src@38770 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 7cbdbfa449e897e0bbdbaace5c7104ae6c68a5c4
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser