Follow-on fixes and naming changes for https://codereview.chromium.org/12086077/

BUG=172573
Review URL: https://codereview.chromium.org/12177018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@180600 0039d316-1c4b-4281-b951-d872f2087c98
void RenderMessageFilter::OnCompletedOpenChannelToNpapiPlugin(
    OpenChannelToNpapiPluginCallback* client) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  DCHECK(ContainsKey(plugin_host_clients_, client));
  plugin_host_clients_.erase(client);
}

void RenderMessageFilter::OnCompletedOpenChannelToNpapiPlugin(
    OpenChannelToNpapiPluginCallback* client) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  DCHECK(ContainsKey(plugin_host_clients_, client));
  plugin_host_clients_.erase(client);
}
