remove tracking code, as it polutes the code readability. Should be added back, in...

remove tracking code, as it polutes the code readability. Should be added back, in a less eficient way, by registering streams instead, so we don't have to pass arround the streams, and the code will be cleaner.

Review URL: https://codereview.chromium.org/26700002

git-svn-id: http://skia.googlecode.com/svn/trunk@11671 2bbb7eff-a529-9590-31e7-b0007b416f81