drm_hwcomposer: Remove threading

Since HWC2 doesn't require the use of threads to implement correct
synchronization, remove some of these threads.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Robert Foss <robert.foss@collabora.com>
diff --git a/glworker.h b/glworker.h
index 158490c..26de55d 100644
--- a/glworker.h
+++ b/glworker.h
@@ -64,6 +64,16 @@
     bool Promote();
   };
 
+  struct {
+    EGLDisplay saved_egl_display = EGL_NO_DISPLAY;
+    EGLContext saved_egl_ctx = EGL_NO_CONTEXT;
+    EGLSurface saved_egl_read = EGL_NO_SURFACE;
+    EGLSurface saved_egl_draw = EGL_NO_SURFACE;
+  } private_;
+
+  int BeginContext();
+  int EndContext();
+
   CachedFramebuffer *FindCachedFramebuffer(
       const sp<GraphicBuffer> &framebuffer);
   CachedFramebuffer *PrepareAndCacheFramebuffer(