Clean up some comments in paint_artifact_compositor.

Make them use the same variable name as the code they describe.

Bug: None
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Id8547edbcc39b591865165bab440165e4d05e7e1
Reviewed-on: https://chromium-review.googlesource.com/1169697
Commit-Queue: Peter Mayo <petermayo@chromium.org>
Reviewed-by: Peter Mayo <petermayo@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583140}

third_party/blink/renderer/platform/graphics/compositing/paint_artifact_compositor.cc

@@ -547,14 +547,14 @@ void PaintArtifactCompositor::LayerizeGroup(
                                  : subgroup_layer.property_tree_state.Clip(),
           &current_group));
     }
-    // At this point pendingLayers.back() is the either a layer from a
+    // At this point pending_layers.back() is the either a layer from a
     // "decomposited" subgroup or a layer created from a chunk we just
     // processed. Now determine whether it could be merged into a previous
     // layer.
     const PendingLayer& new_layer = pending_layers.back();
     DCHECK(!new_layer.requires_own_layer);
     DCHECK_EQ(&current_group, new_layer.property_tree_state.Effect());
-    // This iterates pendingLayers[firstLayerInCurrentGroup:-1] in reverse.
+    // This iterates pending_layers[first_layer_in_current_group:-1] in reverse.
     for (size_t candidate_index = pending_layers.size() - 1;
          candidate_index-- > first_layer_in_current_group;) {
       PendingLayer& candidate_layer = pending_layers[candidate_index];