Don't shrink starting_rect in the first round.

cc/resources/picture_layer_tiling.cc

Index: cc/resources/picture_layer_tiling.cc
diff --git a/cc/resources/picture_layer_tiling.cc b/cc/resources/picture_layer_tiling.cc
index 90250403b65b4e687fcacb085c782acc3e334ff4..594b0238af6206ef4de7b9301aea1c1943f64bb3 100644
--- a/cc/resources/picture_layer_tiling.cc
+++ b/cc/resources/picture_layer_tiling.cc
@@ -530,14 +530,18 @@ gfx::Rect PictureLayerTiling::ExpandRectEquallyToAreaBoundedBy(
   int delta = ComputeExpansionDelta(
       2, 2, starting_rect.width(), starting_rect.height(), target_area);
   gfx::Rect expanded_starting_rect = starting_rect;
-  expanded_starting_rect.Inset(-delta, -delta);
+
+  // Expand but not shink the starting_rect to include small layers that are
+  // in viewport but target_area is smaller than the viewport.
+  if (delta > 0)
+    expanded_starting_rect.Inset(-delta, -delta);
 
   gfx::Rect rect = IntersectRects(expanded_starting_rect, bounding_rect);
   if (rect.IsEmpty()) {
     // The starting_rect and bounding_rect are far away.
     return rect;
   }
-  if (rect == expanded_starting_rect) {
+  if (delta >= 0 && rect == expanded_starting_rect) {
     // The expanded starting rect already covers target_area on bounding_rect.
     return rect;
   }