Fix media_mojo builds

media/mojo/BUILD.gn

Index: media/mojo/BUILD.gn
diff --git a/media/mojo/BUILD.gn b/media/mojo/BUILD.gn
index 20257abfdd56d9db44e24ee74d602fcc76dd32c2..373b5dd22e885d24a7f3ffc9391983a03ef31229 100644
--- a/media/mojo/BUILD.gn
+++ b/media/mojo/BUILD.gn
@@ -16,6 +16,11 @@ source_set("unit_tests") {
     "services/mojo_cdm_allocator_unittest.cc",
   ]
 
+  # As long as //media/mojo/services:lib is a source_set, this needs to be
+  # set as the source will be bundled with this test code.
+  # http://crbug.com/670094
+  defines = [ "MEDIA_MOJO_IMPLEMENTATION" ]
+
   deps = [
     "//base",
     "//base/test:test_support",
@@ -34,14 +39,6 @@ source_set("unit_tests") {
 }
 
 test("media_mojo_unittests") {
-  # crbug.com/676418: Suppress symbol import warnings.
-  if (is_win && is_component_build) {
-    ldflags = [
-      "/ignore:4217",
-      "/ignore:4049",
-    ]
-  }
-
   deps = [
     ":unit_tests",
     "//mojo/edk/test:run_all_unittests",