Update the default GYP flags for sanitizer tools.

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 2024 matching lines @@
       ['enable_mdns==1 or OS=="mac"', {
         'grit_defines': ['-D', 'enable_service_discovery'],
         'enable_service_discovery%': 1
       }],
       ['clang_use_chrome_plugins==1 and OS!="win"', {
         'clang_chrome_plugins_flags': [
           '<!@(<(DEPTH)/tools/clang/scripts/plugin_flags.sh)'
         ],
       }],
 
-      ['asan==1', {
+      ['asan==1 or msan==1 or lsan==1 or tsan==1', {
         'clang%': 1,
         'use_allocator%': 'none',
       }],
       ['ubsan==1', {
         'clang%': 1,
       }],
       ['asan==1 and OS=="mac"', {
         # TODO(glider): we do not strip ASan binaries until the dynamic ASan
         # runtime is fully adopted. See http://crbug.com/242503.
         'mac_strip_release': 0,
       }],
-      ['lsan==1', {
-        'clang%': 1,
-      }],
       ['tsan==1', {
-        'clang%': 1,
         'use_custom_libcxx%': 1,
       }],
       ['msan==1', {
-        'clang%': 1,
+        # Use a just-built, MSan-instrumented libc++ instead of the system-wide
+        # libstdc++. This is required to avoid false positive reports whenever
+        # the C++ standard library is used.
+        'use_custom_libcxx%': 1,
+        # Running the V8-generated code on an ARM simulator is a powerful hack
+        # that allows the tool to see the memory accesses from JITted code.
+        # Without this flag, JS code causes false positive reports from MSan.
+        'v8_target_arch': 'arm64',
       }],
 
       ['OS=="linux" and clang_type_profiler==1', {
         'clang%': 1,
         'clang_use_chrome_plugins%': 0,
         'conditions': [
           ['host_arch=="x64"', {
             'make_clang_dir%': 'third_party/llvm-allocated-type/Linux_x64',
           }],
           ['host_arch=="ia32"', {
@@ skipping 3386 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',
   },
 }