Fail if an isolate entry refers to a missing file.

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 573 matching lines @@
       'use_canvas_skia%': 0,
 
       # Set to "tsan", "memcheck", or "drmemory" to configure the build to work
       # with one of those tools.
       'build_for_tool%': '',
 
       # If no directory is specified then a temporary directory will be used.
       'test_isolation_outdir%': '',
       # True if isolate should fail if the isolate files refer to files
       # that are missing.
-      'test_isolation_fail_on_missing': 0,
+      'test_isolation_fail_on_missing': 1,

[M-A Ruel, 2014/09/18 17:03:20]

One last thing; I'm not 100% sure it's worth keeping the flag and my last
attempt was removing it altogether. I guess there's cases where it could be
valuable temporarily.

[jam, 2014/09/18 17:05:01]

well I'm not sure that all bots will succeed (i.e. waterfall). so I'd like to
land a minimal change, and let's see if things are green. we can then remove it
as a followup.

 
       'wix_path%': '<(DEPTH)/third_party/wix',
 
       # Managed users are enabled by default.
       'enable_managed_users%': 1,
 
       # Platform natively supports discardable memory.
       'native_discardable_memory%': 0,
 
       # Platform sends memory pressure signals natively.
@@ skipping 5188 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',
   },
 }