Reduce absolute paths in generated ninja files

services/catalog/public/tools/catalog.gni

 # Copyright 2016 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.
 
 import("//build/config/dcheck_always_on.gni")
 
 # Generates a static catalog manifest to be loaded at runtime. This manifest
 # contains the union of all individual service manifests specified by the
 # template parameters.
 #
@@ skipping 52 matching lines @@
   action(target_name) {
     testonly = defined(invoker.testonly) && invoker.testonly
 
     script = "//services/catalog/public/tools/generate_manifest.py"
 
     inputs = []
     outputs = [
       output_filename,
     ]
 
-    args = [ "--output=" + rebase_path(output_filename) ]
+    args = [ "--output=" + rebase_path(output_filename, root_build_dir) ]
 
     if (is_debug || dcheck_always_on) {
       args += [ "--pretty" ]
     }
 
     deps = []
     if (defined(invoker.deps)) {
       deps += invoker.deps
     }
 
@@ skipping 110 matching lines @@
 
   source_set(target_name) {
     testonly = defined(invoker.testonly) && invoker.testonly
     sources = get_target_outputs(":$generator_target_name")
     deps = [
       ":$generator_target_name",
       "//base",
     ]
   }
 }