Remove use_aura build arg.

(And also the ui_compositor_image_transport variable.)

Note: You'll want to run "mojob.py gn" again (or manually remove the
use_aura entry in args.gn. Otherwise, gn will yell at you.

R=jamesr@chromium.org

Review URL: https://codereview.chromium.org/1521023002 .

test/test_suite.cc

diff --git a/test/test_suite.cc b/test/test_suite.cc
index e281cff..b6fb2ef 100644
--- a/test/test_suite.cc
+++ b/test/test_suite.cc
@@ -142,12 +142,6 @@
   testing::GTEST_FLAG(catch_exceptions) = false;
 #endif
   EnableTerminationOnHeapCorruption();
-#if defined(OS_LINUX) && defined(USE_AURA)
-  // When calling native char conversion functions (e.g wrctomb) we need to
-  // have the locale set. In the absence of such a call the "C" locale is the
-  // default. In the gtk code (below) gtk_init() implicitly sets a locale.
-  setlocale(LC_ALL, "");
-#endif  // defined(OS_LINUX) && defined(USE_AURA)
 
   // On Android, AtExitManager is created in
   // testing/android/native_test_wrapper.cc before main() is called.