Resume RT-animations after a pauseSurface

Bug: 18203577

The issue occurs as a result of performTraversals() both doing
a window relayout call *and* early-returning because it's not dirty.

To fix this pauseSurface() returns whether or not the RT-side is
"dirty" to force ViewRootImpl to do a draw even if mDirty is
otherwise empty.

Change-Id: I534f367e75d18d273ebf14df3927f5c464ef6bef
diff --git a/libs/hwui/renderthread/RenderProxy.h b/libs/hwui/renderthread/RenderProxy.h
index 4989b14..fd1fe05 100644
--- a/libs/hwui/renderthread/RenderProxy.h
+++ b/libs/hwui/renderthread/RenderProxy.h
@@ -69,7 +69,7 @@
 
     ANDROID_API bool initialize(const sp<ANativeWindow>& window);
     ANDROID_API void updateSurface(const sp<ANativeWindow>& window);
-    ANDROID_API void pauseSurface(const sp<ANativeWindow>& window);
+    ANDROID_API bool pauseSurface(const sp<ANativeWindow>& window);
     ANDROID_API void setup(int width, int height, const Vector3& lightCenter, float lightRadius,
             uint8_t ambientShadowAlpha, uint8_t spotShadowAlpha);
     ANDROID_API void setOpaque(bool opaque);