Gracefully handle child process death in out-of-process plugin loading.

This also queues requests to load plugins, based on http://codereview.chromium.org/8243010/.

BUG=100053
TEST=Install Sonix webcam driver on OS X Lion and try to load a Flash video. It plays.

Review URL: http://codereview.chromium.org/8318028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@106738 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/content/browser/plugin_service.h b/content/browser/plugin_service.h
index 224d2433..2b2c69f 100644
--- a/content/browser/plugin_service.h
+++ b/content/browser/plugin_service.h
@@ -36,6 +36,7 @@
 #endif
 
 class PluginDirWatcherDelegate;
+class PluginLoaderPosix;
 
 namespace base {
 class MessageLoopProxy;
@@ -258,6 +259,10 @@
 
   std::set<PluginProcessHost::Client*> pending_plugin_clients_;
 
+#if defined(OS_POSIX)
+  scoped_refptr<PluginLoaderPosix> plugin_loader_;
+#endif
+
   DISALLOW_COPY_AND_ASSIGN(PluginService);
 };