Tiling priorities in Android Webview.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 94b8bfa1cfac7e9daaa5cef94a4e41954d7a8880..6771558334ed8cc369f72564c62ad963f7bf15e7 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1345,6 +1345,8 @@ void LayerTreeHostImpl::SetExternalDrawConstraints(
     const gfx::Transform& transform,
     const gfx::Rect& viewport,
     const gfx::Rect& clip,
+    const gfx::Rect& external_tiling_rect,
+    const gfx::Transform& external_tiling_transform,
     bool resourceless_software_draw) {
   if (external_transform_ != transform || external_viewport_ != viewport ||
       resourceless_software_draw_ != resourceless_software_draw) {
@@ -1355,6 +1357,11 @@ void LayerTreeHostImpl::SetExternalDrawConstraints(
   external_viewport_ = viewport;
   external_clip_ = clip;
   resourceless_software_draw_ = resourceless_software_draw;
+
+  if (!resourceless_software_draw_) {
+    external_tiling_rect_ = external_tiling_rect;
+    external_tiling_transform_ = external_tiling_transform;
+  }
 }
 
 void LayerTreeHostImpl::SetNeedsRedrawRect(const gfx::Rect& damage_rect) {
@@ -2166,6 +2173,18 @@ gfx::Size LayerTreeHostImpl::DrawViewportSize() const {
   return DeviceViewport().size();
 }
 
+gfx::Rect LayerTreeHostImpl::ExternalTilingRect() const {
+  gfx::Rect empty;
+  if (empty == external_tiling_rect_)
+    return gfx::Rect(DrawViewportSize());
+
+  return external_tiling_rect_;
+}
+
+const gfx::Transform& LayerTreeHostImpl::ExternalTilingTransform() const {
+  return external_tiling_transform_;
+}
+
 gfx::Rect LayerTreeHostImpl::DeviceViewport() const {
   if (external_viewport_.IsEmpty())
     return gfx::Rect(device_viewport_size_);