cc: Simplify the logic for deciding to update tile priorities.

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 3f1c322051dc2afc18e8df8d822d0abe908a1cc8..4ee2226f0bcd542e5a77fb0c1647e7aa2a777a70 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -265,11 +265,22 @@ void PictureLayerImpl::UpdateTilePriorities() {
   if (!tilings_->num_tilings())
     return;
 
-  UpdateLCDTextStatus();
+  double current_frame_time_in_seconds =
+      (layer_tree_impl()->CurrentFrameTimeTicks() -
+       base::TimeTicks()).InSecondsF();
+
+  bool tiling_needs_update = false;
+  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
+    if (tilings_->tiling_at(i)->NeedsUpdateForFrameAtTime(
+            current_frame_time_in_seconds)) {
+      tiling_needs_update = true;
+      break;
+    }
+  }
+  if (!tiling_needs_update)
+    return;
 
-  int current_source_frame_number = layer_tree_impl()->source_frame_number();
-  double current_frame_time = (layer_tree_impl()->CurrentFrameTimeTicks() -
-                               base::TimeTicks()).InSecondsF();
+  UpdateLCDTextStatus();
 
   gfx::Transform current_screen_space_transform = screen_space_transform();
 
@@ -298,8 +309,7 @@ void PictureLayerImpl::UpdateTilePriorities() {
       contents_scale_x(),
       last_screen_space_transform_,
       current_screen_space_transform,
-      current_source_frame_number,
-      current_frame_time,
+      current_frame_time_in_seconds,
       store_screen_space_quads_on_tiles,
       max_tiles_for_interest_area);