[Chromecast][GN] Cleanup gn check errors

BUG= internal b/31275665
TEST= gn check all the platforms

Review-Url: https://codereview.chromium.org/2306383004
Cr-Commit-Position: refs/heads/master@{#417605}

chromecast/common/media/BUILD.gn

@@ -15,6 +15,7 @@ source_set("media") {
   deps = [
     "//base",
     "//chromecast/media/base",
+    "//chromecast/media/cdm",
     "//chromecast/public:public",
     "//media",
   ]