Replace layer id with Element id for tracking scrollbar animation controllers

cc/input/scrollbar_animation_controller_unittest.cc

Index: cc/input/scrollbar_animation_controller_unittest.cc
diff --git a/cc/input/scrollbar_animation_controller_unittest.cc b/cc/input/scrollbar_animation_controller_unittest.cc
index ead11c253f6c5507793f2c8ad8bec459f424bb75..76026013c34c452b9e90fff0ccde6990a38f1aa0 100644
--- a/cc/input/scrollbar_animation_controller_unittest.cc
+++ b/cc/input/scrollbar_animation_controller_unittest.cc
@@ -105,8 +105,10 @@ class ScrollbarAnimationControllerAuraOverlayTest : public testing::Test {
     clip_layer_->test_properties()->AddChild(std::move(scroll_layer));
     host_impl_.active_tree()->SetRootLayerForTesting(std::move(clip));
 
-    v_scrollbar_layer_->SetScrollLayerId(scroll_layer_ptr->id());
-    h_scrollbar_layer_->SetScrollLayerId(scroll_layer_ptr->id());
+    v_scrollbar_layer_->SetScrollInfo(scroll_layer_ptr->id(),

[wkorman, 2017/04/14 18:17:30]

Wondered whether we would be best off naming the method SetScrollElementId(),
since we'll be removing the layer id soon. Info is better during interim but
seems we'll want to end up with just the element id. Just mentioning while
reading, ok to keep as is.

+                                      scroll_layer_ptr->element_id());
+    h_scrollbar_layer_->SetScrollInfo(scroll_layer_ptr->id(),
+                                      scroll_layer_ptr->element_id());
     v_scrollbar_layer_->test_properties()->opacity_can_animate = true;
     h_scrollbar_layer_->test_properties()->opacity_can_animate = true;
     clip_layer_->SetBounds(gfx::Size(100, 100));
@@ -1159,7 +1161,8 @@ class ScrollbarAnimationControllerAndroidTest
     clip->test_properties()->AddChild(std::move(scroll_layer));
     host_impl_.active_tree()->SetRootLayerForTesting(std::move(clip));
 
-    scrollbar_layer_->SetScrollLayerId(scroll_layer_ptr->id());
+    scrollbar_layer_->SetScrollInfo(scroll_layer_ptr->id(),
+                                    scroll_layer_ptr->element_id());
     clip_layer_->SetBounds(gfx::Size(100, 100));
     scroll_layer_ptr->SetBounds(gfx::Size(200, 200));
     host_impl_.active_tree()->BuildLayerListAndPropertyTreesForTesting();