Pull in native_client and build tests.

DEPS.nacl

+import gclient_utils
+import os
+
+path = gclient_utils.FindGclientRoot(os.getcwd())
+execfile(os.path.join(path, 'src', 'DEPS'))  # Include proper Mojo DEPS.
+
+# Now we need to add in NaCl.
+
+vars.update({
+  'nacl_revision': 'c71d65ffcb0e7a1f35eacfd37c327ca5edfa647e', # from svn revision r14268
+})
+
+deps.update({
+  'src/native_client':
+    Var('chromium_git') + '/native_client/src/native_client.git' + '@' + Var('nacl_revision'),
+})
+
+hooks.append({
+  # This downloads binaries for Native Client's newlib toolchain.
+  # Done in lieu of building the toolchain from scratch as it can take
+  # anywhere from 30 minutes to 4 hours depending on platform to build.
+  'name': 'nacltools',
+  'pattern': '.',
+  'action': [
+      'python', 'src/build/download_nacl_toolchains.py',
+      '--packages', 'pnacl_newlib',
+      'sync', '--extract',
+  ],
+})