code from chrome\common.

Also added canvas support and hooked up NPAPI interface functions.
No tests have been added yet, so this is probably not fully ready.

Review URL: http://codereview.chromium.org/291001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@29380 0039d316-1c4b-4281-b951-d872f2087c98