Don't create ink drop container layer in LabelButton constructor

This layer can be created and destroyed as needed when an ink drop is
installed. Creating it on construction adds a cost to every
LabelButton, when there is usually only one ink drop active at a time.

InkDropContainerView already manages this upon adding or removing
ink drop layers, so no additional changes are needed to LabelButton.

Bug: 946738, 960442
Change-Id: If67b443296f85fc296b815d5c61b28683e8d233f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1603182Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658285}

ui/views/controls/button/label_button.cc

@@ -59,8 +59,6 @@ LabelButton::LabelButton(ButtonListener* listener,
   SetTextInternal(text);
 
   AddChildView(ink_drop_container_);
-  ink_drop_container_->SetPaintToLayer();
-  ink_drop_container_->layer()->SetFillsBoundsOpaquely(false);
   ink_drop_container_->SetVisible(false);
 
   AddChildView(image_);