Overscroll and Elasticity for views::ScrollView

cc/proto/layer.proto

Index: cc/proto/layer.proto
diff --git a/cc/proto/layer.proto b/cc/proto/layer.proto
index dfb188de9736158fd4f9b6f5ca101970938c6f25..149b3b4620e830061ff79065d4d7f58cba7af2cc 100644
--- a/cc/proto/layer.proto
+++ b/cc/proto/layer.proto
@@ -73,7 +73,7 @@ message LayerProperties {
   optional PictureLayerProperties picture = 6;
 }
 
-// NEXT ID: 59
+// NEXT ID: 61
 message BaseLayerProperties {
   // The following fields mirror the data stored in Layer::Inputs ----------
   optional Rect update_rect = 46;
@@ -97,6 +97,8 @@ message BaseLayerProperties {
   // repeated FilterOperation background_filters = 13;
   // optional PointF filters_origin = 57
   optional ScrollOffset scroll_offset = 44;
+  optional ScrollOffset overscroll = 59;
+  optional bool can_overscroll = 60;
   optional int32 scroll_clip_layer_id = 37;
   optional bool user_scrollable_horizontal = 38;
   optional bool user_scrollable_vertical = 39;