diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index cd91eb8a693a..34740a8b079e 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -41,6 +41,11 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
+#ifdef MOZ_IPC
+#include "mozilla/dom/ContentParent.h"
+using mozilla::dom::ContentParent;
+#endif
+
 #if defined(XP_OS2) && defined(MOZ_OS2_HIGH_MEMORY)
 // os2safe.h has to be included before os2.h, needed for high mem
 #include <os2safe.h>
@@ -763,6 +768,18 @@ nsXULAppInfo::GetProcessType(PRUint32* aResult)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsXULAppInfo::EnsureContentProcess()
+{
+  if (XRE_GetProcessType() != GeckoProcessType_Default)
+    return NS_ERROR_NOT_AVAILABLE;
+
+  ContentParent* c = ContentParent::GetSingleton();
+  if (!c)
+    return NS_ERROR_NOT_AVAILABLE;
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsXULAppInfo::InvalidateCachesOnRestart()
 {
diff --git a/xpcom/system/nsIXULRuntime.idl b/xpcom/system/nsIXULRuntime.idl
index 39f91d61d33c..69c2a8b7c503 100644
--- a/xpcom/system/nsIXULRuntime.idl
+++ b/xpcom/system/nsIXULRuntime.idl
@@ -44,7 +44,7 @@
  *                    stable/frozen, please contact Benjamin Smedberg.
  */
 
-[scriptable, uuid(cb6078bb-c6b3-4f35-acfd-3b4efa934484)]
+[scriptable, uuid(7685dac8-3637-4660-a544-928c5ec0e714)]
 interface nsIXULRuntime : nsISupports
 {
   /**
@@ -107,4 +107,13 @@ interface nsIXULRuntime : nsISupports
    * fastload data to be re-created.
    */
   void invalidateCachesOnRestart();
+
+  /**
+   * Starts a child process. This method is intented to pre-start a
+   * content child process so that when it is actually needed, it is
+   * ready to go.
+   *
+   * @throw NS_ERROR_NOT_AVAILABLE if not available.
+   */
+  void ensureContentProcess();
 };