Reverting this to see if the Flash crashes on Mac canary are due to this CL.

Reverting this to see if the Flash crashes on Mac canary are due to this CL.

Revert 88773 - Don't retain NPNVWindowNPObject and NPNVPluginElementNPObject twice

Both NPN_GetValue and WebPluginProxy take a reference on access, with
the latter conflating the caller's reference and its internal reference.
To be consistent with WebPluginImpl, let WebPluginProxy only manage its
internal reference and leave the plugin's reference to NPN_GetValue.
Document this in the WebPlugin interface.

Also release plugin-side proxies when WebPluginProxy is destroyed.

R=ananta
BUG=86124
TEST=none


Review URL: http://codereview.chromium.org/6693052

TBR=davidben@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=89221