fix an issue where the screen could stay off

this would happen when toggling on/off/on very fast, the screen
could stay black (while the panel is on).

Bug: 5429724
Change-Id: Ic8aa6aff066e6267923c0d47ef65e314e7bb6d41
diff --git a/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.cpp b/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.cpp
index 59b7e5a..3b7c09e 100644
--- a/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.cpp
+++ b/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.cpp
@@ -122,7 +122,7 @@
 
 DisplayHardwareBase::DisplayHardwareBase(const sp<SurfaceFlinger>& flinger,
         uint32_t displayIndex) 
-    : mCanDraw(true), mScreenAcquired(true)
+    : mScreenAcquired(true)
 {
     mDisplayEventThread = new DisplayEventThread(flinger);
 }
@@ -133,14 +133,9 @@
     mDisplayEventThread->requestExitAndWait();
 }
 
-void DisplayHardwareBase::setCanDraw(bool canDraw)
-{
-    mCanDraw = canDraw;
-}
-
 bool DisplayHardwareBase::canDraw() const
 {
-    return mCanDraw && mScreenAcquired;
+    return mScreenAcquired;
 }
 
 void DisplayHardwareBase::releaseScreen() const
diff --git a/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.h b/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.h
index 3ebc7b6..ef2df43 100644
--- a/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.h
+++ b/services/surfaceflinger/DisplayHardware/DisplayHardwareBase.h
@@ -43,7 +43,6 @@
     bool isScreenAcquired() const;
 
     bool canDraw() const;
-    void setCanDraw(bool canDraw);
 
 
 private:
@@ -74,7 +73,6 @@
     };
 
     sp<DisplayEventThreadBase>  mDisplayEventThread;
-    mutable int                 mCanDraw;
     mutable int                 mScreenAcquired;
 };