Ready to enable MSan build for PDFium

DEPS

 use_relative_paths = True
 
 vars = {
   'chromium_git': 'https://chromium.googlesource.com',
   'pdfium_git': 'https://pdfium.googlesource.com',
 
   'android_ndk_revision': '5022f40f12953c02b2614c5f7beb981ec5d0e833',
   'build_revision': 'b73bafdd0ff0efc8835de6e646b47eec0a2a38a4',
   'buildtools_revision': '5fd66957f08bb752dca714a591c84587c9d70762',
   'catapult_revision': '327256cb1c387e62a2c7e6960e2398867665fb51',
   'clang_revision': '797371be0a75c9892d6acb486d0430915ea538a6',
   'cygwin_revision': 'c89e446b273697fadf3a10ff1007a97c0b7de6df',
   'gen_library_loader_revision': '916d4acd8b2cde67a390737dfba90b3c37de23a1',
   'gmock_revision': '29763965ab52f24565299976b936d1265cb6a271',
   'gtest_revision': '8245545b6dc9c4703e6496d1efd19e975ad2b038',
   'icu_revision': '2341038bf72869a5683a893a2b319a48ffec7f62',
+  'instrumented_lib_revision': '45f5814b1543e41ea0be54c771e3840ea52cca4a',
   'pdfium_tests_revision': '06411790a46e6497e5293f921ea9aa9fb2615e41',
   'skia_revision': 'b55ebf071dce33794f5518dcdc3a9af006285796',
   'tools_memory_revision': '427f10475e1a8d72424c29d00bf689122b738e5d',
   'trace_event_revision': '6232c13e4edb36c84c61653fdae5a4afb5af9745',
   'v8_revision': 'a964163e6ac4f1124b22ea7e46b8afe26dec02e0',
 }
 
 deps = {
   "base/trace_event/common":
     Var('chromium_git') + "/chromium/src/base/trace_event/common.git@" +
@@ skipping 10 matching lines @@
 
   "testing/gmock":
     Var('chromium_git') + "/external/googlemock.git@" + Var('gmock_revision'),
 
   "testing/gtest":
     Var('chromium_git') + "/external/googletest.git@" + Var('gtest_revision'),
 
   "third_party/icu":
     Var('chromium_git') + "/chromium/deps/icu.git@" + Var('icu_revision'),
 
+  "third_party/instrumented_libraries":
+    Var('chromium_git') + "/chromium/src/third_party/instrumented_libraries.git@" + Var('instrumented_lib_revision'),
+
   "third_party/skia":
     Var('chromium_git') + '/skia.git' + '@' +  Var('skia_revision'),
 
   "tools/clang":
     Var('chromium_git') + "/chromium/src/tools/clang@" +  Var('clang_revision'),
 
   "tools/generate_library_loader":
     Var('chromium_git') + "/chromium/src/tools/generate_library_loader@" +
         Var('gen_library_loader_revision'),
 
@@ skipping 116 matching lines @@
     'action': ['python',
                'pdfium/tools/clang/scripts/update.py'
     ],
   },
   {
     # Update the Windows toolchain if necessary.
     'name': 'win_toolchain',
     'pattern': '.',
     'action': ['python', 'pdfium/build/vs_toolchain.py', 'update'],
   },
+  {
+    # Pull sanitizer-instrumented third-party libraries if requested via
+    # GYP_DEFINES.
+    'name': 'instrumented_libraries',
+    'pattern': '\\.sha1',
+    'action': ['python', 'pdfium/third_party/instrumented_libraries/scripts/download_binaries.py'],
+  },
+
 ]