Remove using directives ("using namespace x") in chromecast/.

Bug: 82078
Change-Id: Ie0f4f0c7a5a78eb8a5086721b6146c00401034ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879996
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Sean Topping <seantopping@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709968}

chromecast/ui/vector_icons/vector_icons.cc.template

@@ -8,15 +8,15 @@
 #include "chromecast/ui/vector_icons.h"
 
 #include "base/logging.h"
+#include "components/vector_icons/cc_macros.h"
 #include "ui/gfx/vector_icon_types.h"
 
-#include "components/vector_icons/cc_macros.h"
+#define DECLARE_VECTOR_COMMAND(x) using gfx::x;
+DECLARE_VECTOR_COMMANDS
 
 namespace chromecast {
 namespace vector_icons {
 
-using namespace gfx;
-
 TEMPLATE_PLACEHOLDER
 
 }  // namespace vector_icons