surfaceflinger: replace early suspend with binder call from PowerManager

SurfaceFlinger will no longer directly synchronize with early suspend.
Instead, PowerManagerService will synchronize with SurfaceFlinger to
ensure that a black frame has been drawn on the display, and then
trigger all early suspend handlers.

Change-Id: I07acdd628440d23fdb69db94319ec5d65d3f4919
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index d9c2033..f0e955b 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -182,11 +182,10 @@
     virtual status_t                    turnElectronBeamOff(int32_t mode);
     virtual status_t                    turnElectronBeamOn(int32_t mode);
 
-
             // called when screen needs to turn off
-            void screenReleased();
+    virtual void                        blank();
             // called when screen is turning back on
-            void screenAcquired();
+    virtual void                        unblank();
 
             // called on the main thread in response to screenReleased()
             void onScreenReleased();