Fix errors found in Mac gn component builds

media/cast/BUILD.gn

Index: media/cast/BUILD.gn
diff --git a/media/cast/BUILD.gn b/media/cast/BUILD.gn
index 2262c7b6cbc5f3e6d78c2c0712002865fc0681d9..b6df09f4e874838ae7bbf76433b65d26749229be 100644
--- a/media/cast/BUILD.gn
+++ b/media/cast/BUILD.gn
@@ -163,12 +163,25 @@ source_set("sender") {
     ]
   }
 
+  libs = []
+
   # iOS and OS X encoders
   if (is_ios || is_mac) {
     sources += [
       "sender/h264_vt_encoder.cc",
       "sender/h264_vt_encoder.h",
     ]
+
+    libs += [
+      "CoreVideo.framework",
+    ]
+  }
+
+  if (is_mac) {
+    # Required by audio_encoder.cc.
+    libs += [
+      "AudioToolbox.framework",
+    ]
   }
 }