Committing on behalf of knorton@google.com
Committing on behalf of knorton@google.com

Fixes a threading issue in PluginInstance.
PluginThreadAsyncCall is supposed to provide a thread safe way of
enqueing a callback onto the plugin thread. Currently, it unsafely
adds a reference to the PluginInstance when the callback is enqueued.
This patch converts PluginInstance from RefCounted to
RefCountedThreadSafe.

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@5706 0039d316-1c4b-4281-b951-d872f2087c98

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