Reduce absolute paths in generated ninja files

testing/libfuzzer/fuzzer_test.gni

 # 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.
 
 # Defines fuzzer_test.
 #
 import("//build/config/features.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//testing/test.gni")
 
@@ skipping 30 matching lines @@
       assert(!(defined(invoker.seed_corpus) && defined(invoker.seed_corpuses)),
              "Do not use both seed_corpus and seed_corpuses for $target_name.")
 
       out = "$root_build_dir/$target_name" + "_seed_corpus.zip"
 
       action(target_name + "_seed_corpus") {
         script = "//testing/libfuzzer/archive_corpus.py"
 
         args = [
           "--output",
-          rebase_path(out),
+          rebase_path(out, root_build_dir),
         ]
 
         if (defined(invoker.seed_corpus)) {
-          args += [ rebase_path(invoker.seed_corpus) ]
+          args += [ rebase_path(invoker.seed_corpus, root_build_dir) ]
         }
 
         if (defined(invoker.seed_corpuses)) {
           foreach(seed_corpus_path, invoker.seed_corpuses) {
-            args += [ rebase_path(seed_corpus_path) ]
+            args += [ rebase_path(seed_corpus_path, root_build_dir) ]
           }
         }
 
         outputs = [
           out,
         ]
 
         deps = [
           "//testing/libfuzzer:seed_corpus",
         ]
@@ skipping 15 matching lines @@
         }
         test_deps += [ ":" + target_name + "_dict_copy" ]
       }
 
       # Generate .options file.
       config_name = target_name + ".options"
       action(config_name) {
         script = "//testing/libfuzzer/gen_fuzzer_config.py"
         args = [
           "--config",
-          rebase_path("$root_build_dir/" + config_name),
+          rebase_path("$root_build_dir/" + config_name, root_build_dir),
         ]
 
         if (defined(invoker.dict)) {
           args += [
             "--dict",
-            rebase_path("$root_build_dir/" + invoker.target_name + ".dict"),
+            rebase_path("$root_build_dir/" + invoker.target_name + ".dict",
+                        root_build_dir),
           ]
         }
 
         if (defined(invoker.libfuzzer_options)) {
           args += [ "--libfuzzer_options" ]
           args += invoker.libfuzzer_options
         }
 
         outputs = [
           "$root_build_dir/$config_name",
@@ skipping 46 matching lines @@
       assert(invoker.seed_corpuses == [] || invoker.seed_corpuses != [])
     }
     assert(!defined(invoker.check_includes) || invoker.check_includes != [])
     assert(!defined(invoker.include_dirs) || invoker.include_dirs != [])
     assert(!defined(invoker.defines) || invoker.defines != [])
 
     group(target_name) {
     }
   }
 }