hwc: Use displayFrame information in caching

In some use-cases layer handle is not changing but
displayFrame is changing, resulting flickers.

Change-Id: I4e5a2756efe76754ab517f65dae75fc07db48435
diff --git a/libhwcomposer/hwc_copybit.h b/libhwcomposer/hwc_copybit.h
index a7ce43e..9793b4a 100644
--- a/libhwcomposer/hwc_copybit.h
+++ b/libhwcomposer/hwc_copybit.h
@@ -60,6 +60,7 @@
     struct LayerCache {
       int layerCount;
       buffer_handle_t hnd[MAX_NUM_APP_LAYERS];
+      hwc_rect_t displayFrame[MAX_NUM_APP_LAYERS];
       /* c'tor */
       LayerCache();
       /* clear caching info*/
@@ -133,6 +134,7 @@
                   int dpy);
     int checkDirtyRect(hwc_context_t *ctx, hwc_display_contents_1_t *list,
                   int dpy);
+    bool isLayerChanging(hwc_display_contents_1_t *list, int k);
 };
 
 }; //namespace qhwc