Add a new gyp define to be used by the swarm master.

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 320 matching lines @@
 
       # Whether tests targets should be run, archived or just have the
       # dependencies verified. All the tests targets have the '_run' suffix,
       # e.g. base_unittests_run runs the target base_unittests. The test target
       # always calls tools/isolate/isolate.py. See the script's --help for more
       # information and the valid --mode values. Meant to be overriden with
       # GYP_DEFINES.
       # TODO(maruel): Converted the default from 'check' to 'noop' so work can
       # be done while the builders are being reconfigured to check out test data
       # files.
-      'tests_run%': 'noop',
+      'test_isolation_mode%': 'noop',
+      # It must not be '<(PRODUCT_DIR)' alone, the '/' is necessary otherwise
+      # gyp will remove duplicate flags, causing isolate.py to be confused.
+      'test_isolation_outdir%': '<(PRODUCT_DIR)/',
 
        # Force rlz to use chrome's networking stack.
       'force_rlz_use_chrome_net%': 1,
 
       'platformsdk_path%': '<(DEPTH)/third_party/platformsdk_win7/files',
       'wix_path%': '<(DEPTH)/third_party/wix',
 
       'conditions': [
         # TODO(epoger): Figure out how to set use_skia=1 for Mac outside of
         # the 'conditions' clause.  Initial attempts resulted in chromium and
@@ skipping 199 matching lines @@
     'enable_web_intents_tag%': '<(enable_web_intents_tag)',
     'enable_plugin_installation%': '<(enable_plugin_installation)',
     'enable_protector_service%': '<(enable_protector_service)',
     'enable_session_service%': '<(enable_session_service)',
     'enable_themes%': '<(enable_themes)',
     'enable_background%': '<(enable_background)',
     'enable_promo_resource_service%': '<(enable_promo_resource_service)',
     'linux_use_gold_binary%': '<(linux_use_gold_binary)',
     'linux_use_gold_flags%': '<(linux_use_gold_flags)',
     'use_canvas_skia%': '<(use_canvas_skia)',
-    'tests_run%': '<(tests_run)',
+    'test_isolation_mode%': '<(test_isolation_mode)',
+    'test_isolation_outdir%': '<(test_isolation_outdir)',
     'enable_automation%': '<(enable_automation)',
     'force_rlz_use_chrome_net%': '<(force_rlz_use_chrome_net)',
     'enable_task_manager%': '<(enable_task_manager)',
     'platformsdk_path%': '<(platformsdk_path)',
     'wix_path%': '<(wix_path)',
     'android_upstream_bringup%': '<(android_upstream_bringup)',
 
     # Use system yasm instead of bundled one.
     'use_system_yasm%': 0,
 
@@ skipping 2488 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }