Fix PPB_Audio_Proxy handling of file descriptors.
Fix PPB_Audio_Proxy handling of file descriptors.

Previous code was closing a file descriptor it shouldn't causing trouble when the real owner tried to close it again.

BUG=none
TEST=with pepper flash, load a youtube video with sound, reload the page, should see no assert.

Review URL: http://codereview.chromium.org/6528004

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@74894 0039d316-1c4b-4281-b951-d872f2087c98

gavinp/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,adobe/chromium,ropik/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,ropik/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,adobe/chromium,gavinp/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,gavinp/chromium,ropik/chromium