Collect GPU info on Mac through IO registry for dual GPU systems.
Collect GPU info on Mac through IO registry for dual GPU systems.

Go through IO Registry to locate PCI based video cards on Mac.  If there are two video cards and one of them is Intel, we assume Intel GPU is the integrated one and the other is the discrete one.  Chromium GPU process should always use the discrete one (if Mac is handling automatic card switching), and we identify the discrete card in preliminary GPU info collection so we could run through GPU software rendering list and set up the renderer process with approriate GPU feature capabilities.

Note that if the IO registry method fails, we fallback to the original "GPU locating through current display" method, so this CL should be pretty safe.

BUG=75208,75220
TEST=gpu acceleration is enabled on Mac with Intel/ATI dual GPU.
Review URL: http://codereview.chromium.org/6879023

git-svn-id: http://src.chromium.org/svn/trunk/src@82202 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 2f93bc949c61bc821a917a435325e6239d462e2e
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