Issue #2654 - Remove pre-allocated process manager.

Resolves #2654

dom/ipc/PContent.ipdl

@@ -400,7 +400,6 @@ child:
 
     async AppInfo(nsCString version, nsCString buildID, nsCString name, nsCString UAName,
                   nsCString ID, nsCString vendor);
-    async AppInit();
 
     /**
      * Send ServiceWorkerRegistrationData to child process.
@@ -757,9 +756,6 @@ parent:
     // Notify the parent of the presence or absence of private docshells
     async PrivateDocShellsExist(bool aExist);
 
-    // Tell the parent that the child has gone idle for the first time
-    async FirstIdle();
-
     async AudioChannelServiceStatus(bool aActiveTelephonyChannel,
                                     bool aContentOrNormalChannel,
                                     bool aAnyActiveChannel);