Remoting: Add missing Gyp dependency on the "prep_toolchain" target

remoting/remoting_key_tester.gypi

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'includes': [
     '../build/common_untrusted.gypi',
   ],
 
   'variables': {
@@ skipping 77 matching lines @@
             'build_pnacl_newlib': 1,
             'extra_deps_pnacl_newlib': [
               '>(tc_lib_dir_pnacl_newlib)/libppapi.a',
               '>(tc_lib_dir_pnacl_newlib)/libppapi_cpp.a',
             ],
           },
           'link_flags': [
             '-lppapi_stub',
             '-lppapi_cpp',
           ],
+          'dependencies': [
+            # TODO(mseaborn): Remove need for this (https://crbug.com/456902).

[Łukasz Anforowicz, 2015/02/09 20:57:07]

Mark, do you also want/need a similar TODO comment in remoting/remoting_nacl.gyp
(which also lists prep_toolchain as a dependency)?

BTW: My apologies for missing this dependency.  Are there some pre-check-in
steps that I should have done (that would have caught the missing dependency
before landing crrev.com/884703006)?

[Mark Seaborn, 2015/02/17 22:56:35]

I thought about doing that, but since ncbray is actively working on removing the
need for this (https://crbug.com/456902), I didn't think it would be worth
adding comments to other locations.  Hopefully the fix will be committed in
Chromium by tomorrow.
No worries.  We were only catching this by manual review before, but ncbray's
cleanup will remove the need for that.

+            '<(DEPTH)/native_client/tools.gyp:prep_toolchain',
+          ],
         },  # end of target 'remoting_key_tester_pexe'
       ],
     }]
   ],
 }