Remove PNaCl's RequestFirstInstall, use resource throttle instead

ppapi/api/private/ppb_nacl_private.idl

Index: ppapi/api/private/ppb_nacl_private.idl
diff --git a/ppapi/api/private/ppb_nacl_private.idl b/ppapi/api/private/ppb_nacl_private.idl
index 3b965e9b63b891dbac907381688f611f3a89e629..7a52372fdd6fac03a6f116fa2b1eb13614225cad 100644
--- a/ppapi/api/private/ppb_nacl_private.idl
+++ b/ppapi/api/private/ppb_nacl_private.idl
@@ -87,14 +87,6 @@ interface PPB_NaCl_Private {
                                 [in] uint32_t desired_access,
                                 [in] uint32_t options);
 
-  /* Check if PNaCl is installed and attempt to install if necessary.
-   * Callback is called when the check is done and PNaCl is already installed,
-   * or after an on-demand install is attempted. Called back with PP_OK if
-   * PNaCl is available. Called back with an error otherwise.
-   */
-  int32_t EnsurePnaclInstalled([in] PP_Instance instance,
-                               [in] PP_CompletionCallback callback);
-
   /* Returns a read-only file descriptor of a file rooted in the Pnacl
    * component directory, or an invalid handle on failure.
    */