Move default sanitizer options into build/ so that WebRTC can import them.

build/sanitizers/sanitizers.gyp

Index: build/sanitizers/sanitizers.gyp
diff --git a/build/sanitizers/sanitizers.gyp b/build/sanitizers/sanitizers.gyp
new file mode 100644
index 0000000000000000000000000000000000000000..cbe7ec015d7506990f8e4b001a3a546f69905998
--- /dev/null
+++ b/build/sanitizers/sanitizers.gyp
@@ -0,0 +1,52 @@
+# Copyright 2014 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.
+
+{
+  'targets': [
+    {
+      'target_name': 'sanitizer_options',
+      'type': 'static_library',
+      'toolsets': ['host', 'target'],
+      'variables': {
+         # Every target is going to depend on sanitizer_options, so allow
+         # this one to depend on itself.
+         'prune_self_dependency': 1,
+         # Do not let 'none' targets depend on this one, they don't need to.
+         'link_dependency': 1,
+       },
+      'sources': [
+        'sanitizer_options.cc',
+      ],
+      'include_dirs': [
+        '../..',
+      ],
+      # Some targets may want to opt-out from ASan, TSan and MSan and link
+      # without the corresponding runtime libraries. We drop the libc++
+      # dependency and omit the compiler flags to avoid bringing instrumented
+      # code to those targets.
+      'conditions': [
+        ['use_custom_libcxx==1', {
+          'dependencies!': [
+            '../../third_party/libc++/libc++.gyp:libcxx_proxy',
+          ],
+        }],
+        ['tsan==1', {
+          'sources': [
+            'tsan_suppressions.cc',
+          ],
+        }],
+      ],
+      'cflags/': [
+        ['exclude', '-fsanitize='],
+        ['exclude', '-fsanitize-'],
+      ],
+      'direct_dependent_settings': {
+        'ldflags': [
+          '-Wl,-u_sanitizer_options_link_helper',
+        ],
+      },
+    },
+  ],
+}
+