Part 3 of 'Polish dragging of ToolStrips': Restrict the horizontal and vertical motions of the toolstrips so that they cannot be dragged out of the extension shelf.
Part 3 of 'Polish dragging of ToolStrips': Restrict the horizontal and vertical motions of the toolstrips so that they cannot be dragged out of the extension shelf.

BUG=www.crbug.com/18443
TEST=none

Review URL: http://codereview.chromium.org/251004

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@27290 0039d316-1c4b-4281-b951-d872f2087c98

gavinp/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium