GN: component build was broken on unit_tests_main

TEST=gn args out/gn --args="is_component_build=true"; \
    gn gen out/gn && ninja -C out/gn unit_tests_main
BUG=n/a

Review URL: https://codereview.chromium.org/1139893003

Cr-Commit-Position: refs/heads/master@{#329676}

chrome/browser/media/router/BUILD.gn

@@ -59,6 +59,7 @@ source_set("unit_tests") {
     "//chrome/test:test_support",
     "//testing/gmock",
     "//testing/gtest",
+    "//third_party/cld_2:cld2_static",
     "//third_party/mojo/src/mojo/public/cpp/bindings",
   ]
   sources = [