Revert 86532 - Revert 86517 - Don't terminate plugin processes from the browser during browser sh...

Revert 86532 - Revert 86517 - Don't terminate plugin processes from the browser during browser shutdown. This is to allow the plugins to
shutdown gracefully, i.e. NP_Shutdown gets called. To ensure that we handle the case of a hung plugin, we handle
the OnChannelError notification in the IPC message filter implementation in the plugin process and post a delayed 
task to kill the process.

Fixes bug http://code.google.com/p/chromium/issues/detail?id=48178

BUG=48178
Review URL: http://codereview.chromium.org/6992006

TBR=ananta@chromium.org
Review URL: http://codereview.chromium.org/7065048

TBR=nsylvain@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=86554