Remove Widevine Dylib from signing list

Rather than requiring Chrome to sign the Mac dylib, Widevine will upload
signed binaries to Chrome. To stop Chrome from signing the library, this
change removes it from the list of dylibs to be signed.

Bug: 702834
Change-Id: I4295b12329f863856e6482f17b633710d3f2112b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1967606Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Commit-Queue: Aaron Vaage <vaage@google.com>
Cr-Commit-Position: refs/heads/master@{#735015}

chrome/installer/mac/signing/chromium_config.py

@@ -17,7 +17,7 @@ class ChromiumCodeSignConfig(BuildPropsCodeSignConfig):
     def optional_parts(self):
         # This part requires src-internal, so it is not required for a Chromium
         # build signing.
-        return set(('libwidevinecdm.dylib',))
+        return set()
 
     @property
     def provisioning_profile_basename(self):

chrome/installer/mac/signing/signing.py

@@ -127,7 +127,6 @@ def get_parts(config):
         'libGLESv2.dylib',
         'libswiftshader_libEGL.dylib',
         'libswiftshader_libGLESv2.dylib',
-        'WidevineCdm/_platform_specific/mac_x64/libwidevinecdm.dylib',
     )
     for library in dylibs:
         library_basename = os.path.basename(library)

chrome/installer/mac/signing/signing_test.py

@@ -326,13 +326,17 @@ class TestSignChrome(unittest.TestCase):
 
     @mock.patch('signing.signing._sanity_check_version_keys')
     def test_sign_chrome_optional_parts(self, *args, **kwargs):
+        # The optional library must be an actual library from the dylibs list in
+        # "signing.py".
+        optional_library = 'libEGL.dylib'
+        optional_identifier = 'libEGL'
 
         def _fail_to_sign(*args):
-            if args[2].identifier == 'libwidevinecdm':
+            if args[2].identifier == optional_identifier:
                 raise FileNotFoundError(args[2].path)
 
         def _file_exists(*args):
-            return not args[0].endswith('libwidevinecdm.dylib')
+            return not args[0].endswith(optional_library)
 
         kwargs['sign_part'].side_effect = _fail_to_sign
 
@@ -349,7 +353,7 @@ class TestSignChrome(unittest.TestCase):
 
                 @property
                 def optional_parts(self):
-                    return set(('libwidevinecdm.dylib',))
+                    return set((optional_library,))
 
             # With the part marked as optional, it should succeed.
             config = model.Distribution().to_config(Config())