Add image decode task instrumentation for devtools
DevTools need to distinguish imade decode events coming from different
pages within the same process. We used to check for image decode events
coming from within paint or rasterization of known layers, but now
image decodes may happen as independent top-level tasks. The patch adds
instrumentation for such tasks that assoicates tasks wiht layer ids.
Related blink patch: https://codereview.chromium.org/
15011005/
BUG=173184
R=nduca@chromium.org
Review URL: https://codereview.chromium.org/
14588008
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@201064 0039d316-1c4b-4281-b951-d872f2087c98