Iframe placeholders, security and resizing
This change adds javascript to fill in the YouTube placeholders
created by the distiller. the content security policy now allows
for iframes from all sources (distiller closely controls which
iframes are allowed). Some css has also been added to appropriately
resize these iframes when the page is resized.
This change will not work correctly by itself, it depends on the
following CL to work correctly:
https://codereview.chromium.org/
1015463004
BUG=468862
Review URL: https://codereview.chromium.org/
880983007
Cr-Commit-Position: refs/heads/master@{#323934}