drm_hwcomposer: refactor Worker

Make use of standard library mutex and conditions which simplifies use
of condition variables and benefits from things like scoped locking.

Also add tests to make sure it runs as expected.

Change-Id: Iaf92e17e1f6757dce490eddee61f84cb1f953b0c

1 files changed, 2 insertions, 2 deletions

diff --git a/vsyncworker.h b/vsyncworker.h
index a1ba1a5..787152e 100644
--- a/vsyncworker.h
+++ b/vsyncworker.h
@@ -41,9 +41,9 @@ class VSyncWorker : public Worker {
   ~VSyncWorker() override;
 
   int Init(DrmResources *drm, int display);
-  int RegisterCallback(std::shared_ptr<VsyncCallback> callback);
+  void RegisterCallback(std::shared_ptr<VsyncCallback> callback);
 
-  int VSyncControl(bool enabled);
+  void VSyncControl(bool enabled);
 
  protected:
   void Routine() override;