Remove the _cpp_sources target from mojom.

third_party/WebKit/Source/platform/BUILD.gn

 # 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 import("//third_party/WebKit/public/public_features.gni")
 import("//third_party/WebKit/Source/build/scripts/scripts.gni")
@@ skipping 220 matching lines @@
       # then delete the precompile.c.obj file, then build again.
       cflags_c = [ "/wd4206" ]
     }
   }
 }
 
 component("platform") {
   visibility = []  # Allow re-assignment of list.
   visibility = [
     "//third_party/WebKit/*",
-    "//url/mojo:url_mojom_origin_blink_cpp_sources",
-    "//url/mojo:url_mojom_gurl_blink_cpp_sources",
+    "//url/mojo:url_mojom_origin_blink",
+    "//url/mojo:url_mojom_gurl_blink",
   ]
   output_name = "blink_platform"
 
   sources = [
     "AsyncFileSystemCallbacks.h",
     "CalculationValue.h",
     "ContentDecryptionModuleResult.h",
     "ContentSettingCallbacks.cpp",
     "ContentSettingCallbacks.h",
     "ContextMenu.cpp",
@@ skipping 1833 matching lines @@
     "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     ":test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }