ui/gl: Clear EGL bindings on mac during teardown.

The fact that we initialize EGL bindings in tests but don't clear them
on teardown was making tests unhappy.

R=piman@chromium.org

BUG: 899985
Change-Id: Id5e103974379f1fca18d9ec67768f9fc72f65061
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1566280
Commit-Queue: Khushal <khushalsagar@chromium.org>
Auto-Submit: Khushal <khushalsagar@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#650503}

ui/gl/init/gl_initializer_mac.cc

@@ -228,6 +228,9 @@ void InitializeDebugGLBindings() {
 
 void ShutdownGLPlatform() {
   ClearBindingsGL();
+#if BUILDFLAG(USE_EGL_ON_MAC)
+  ClearBindingsEGL();
+#endif  // BUILDFLAG(USE_EGL_ON_MAC)
 }
 
 }  // namespace init