PPAPI: Set custom user agent in headers, if applicable.

PPAPI: Set custom user agent in headers, if applicable.

Note: This requires a WebKit change to not overwrite the user agent.

BUG=134615
TEST=With a Flapper that sets the user agent under the appropriate
     circumstances (not yet available), check that http://10tv.nana10.co.il/
     streams properly. Or sniff and check that requests to port 1935 have
     "Shockwave Flash" as user agent.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=145963

[viettrungluu, 2012-07-10 21:18:00]

For this to work, this needs the other patches
(https://bugs.webkit.org/show_bug.cgi?id=90893 , which is dependent on
https://chromiumcodereview.appspot.com/10735037/ ).

[brettw, 2012-07-10 21:20:17]

lgtm