Fix memory leak of "screen size bitmap" (e.g. 1.5M if 750x548)  that happened on *every page view* on OSX.
Fix memory leak of "screen size bitmap" (e.g. 1.5M if 750x548) 
that happened on *every page view* on OSX.

VSIZE/RSIZE now hovers around 500M/30M instead of growing to 1.3G/260M
within a few minutes.

Surprisingly, Chromium.app seems quite a bit snappier!

The essence of the change is that SkBitmap::setPixels() does NOT take
ownership of the pointer, whereas SkBitmap::allocPixels() both
allocates and owns.

Review URL: http://codereview.chromium.org/39307

git-svn-id: http://src.chromium.org/svn/trunk/src@11196 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: c3c17d6b5dccef887e349174b9f28085c3b28033
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