Change test_isolation_mode default from noop to check

build/isolate.gypi

Index: build/isolate.gypi
diff --git a/build/isolate.gypi b/build/isolate.gypi
index 6ddc3fef2bfd1a3748f1103fff2c9fe18d9e609d..d7523fdfb389028747bca14cc61ceb2d82ca407b 100644
--- a/build/isolate.gypi
+++ b/build/isolate.gypi
@@ -40,7 +40,6 @@
       'rule_name': 'isolate',
       'extension': 'isolate',
       'inputs': [
-        '<(RULE_INPUT_PATH)',
         # Disable file tracking by the build driver for now. This means the
         # project must have the proper build-time dependency for their runtime
         # dependency. This improves the runtime of the build driver since it
@@ -60,6 +59,7 @@
         'python',
         '<(DEPTH)/tools/swarm_client/isolate.py',
         '<(test_isolation_mode)',
+        '--outdir', '<(test_isolation_outdir)',
         '--variable', 'PRODUCT_DIR', '<(PRODUCT_DIR)',
         '--variable', 'OS', '<(OS)',
         '--variable', 'chromeos', '<(chromeos)',
@@ -72,8 +72,11 @@
             '--outdir', '<(PRODUCT_DIR)/<(test_isolation_outdir)',
           ],
         }],
+        ['test_isolation_fail_on_missing == 0', {
+            'action': ['--ignore_broken_items']
+          },
+        ],
       ],
-
       'msvs_cygwin_shell': 0,
     },
   ],