Fix a pepper plugin process crash which occurs if we receive input events for a deleted plugin. This could happen in the multi process plugin scenario where the renderer could send events for deleted plugins in the context of outgoing sync calls.
Fix a pepper plugin process crash which occurs if we receive input events for a deleted plugin. This could happen
in the multi process plugin scenario where the renderer could send events for deleted plugins in the context of outgoing
sync calls.

Fixes bug http://code.google.com/p/flapper/issues/detail?id=87
Review URL: http://codereview.chromium.org/8073017

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@103377 0039d316-1c4b-4281-b951-d872f2087c98

gavinp/chromium,ropik/chromium,adobe/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,ropik/chromium,ropik/chromium,gavinp/chromium