Remove the apps grid page switcher from the experimental app list.

This CL removes the page switcher from the experimental app list's apps
grid view. The normal app list should be unaffected.

BUG=406222

Review URL: https://codereview.chromium.org/521823004

Cr-Commit-Position: refs/heads/master@{#292905}

ui/app_list/views/apps_grid_view.cc

@@ -62,6 +62,7 @@ const int kDragBufferPx = 20;
 // Padding space in pixels for fixed layout.
 const int kLeftRightPadding = 20;
 const int kTopPadding = 1;
+const int kBottomPadding = 24;
 
 // Padding space in pixels between pages.
 const int kPagePadding = 40;
@@ -372,8 +373,10 @@ AppsGridView::AppsGridView(AppsGridViewDelegate* delegate)
           : PaginationController::SCROLL_AXIS_HORIZONTAL;
   pagination_controller_.reset(
       new PaginationController(&pagination_model_, scroll_axis));
-  page_switcher_view_ = new PageSwitcher(&pagination_model_);
-  AddChildView(page_switcher_view_);
+  if (!switches::IsExperimentalAppListEnabled()) {
+    page_switcher_view_ = new PageSwitcher(&pagination_model_);
+    AddChildView(page_switcher_view_);
+  }
 }
 
 AppsGridView::~AppsGridView() {
@@ -622,10 +625,12 @@ void AppsGridView::UpdateDrag(Pointer pointer, const gfx::Point& point) {
   else
     StopPageFlipTimer();
 
-  gfx::Point page_switcher_point(last_drag_point_);
-  views::View::ConvertPointToTarget(this, page_switcher_view_,
-                                    &page_switcher_point);
-  page_switcher_view_->UpdateUIForDragPoint(page_switcher_point);
+  if (page_switcher_view_) {
+    gfx::Point page_switcher_point(last_drag_point_);
+    views::View::ConvertPointToTarget(
+        this, page_switcher_view_, &page_switcher_point);
+    page_switcher_view_->UpdateUIForDragPoint(page_switcher_point);
+  }
 
   if (!EnableFolderDragDropUI()) {
     if (last_drop_target != drop_target_)
@@ -875,8 +880,9 @@ gfx::Size AppsGridView::GetPreferredSize() const {
   const gfx::Insets insets(GetInsets());
   const gfx::Size tile_size = gfx::Size(kPreferredTileWidth,
                                         kPreferredTileHeight);
-  const int page_switcher_height =
-      page_switcher_view_->GetPreferredSize().height();
+  int page_switcher_height = kBottomPadding;
+  if (page_switcher_view_)
+    page_switcher_height = page_switcher_view_->GetPreferredSize().height();
   return gfx::Size(
       tile_size.width() * cols_ + insets.width(),
       tile_size.height() * rows_per_page_ +
@@ -911,12 +917,14 @@ void AppsGridView::Layout() {
   }
   views::ViewModelUtils::SetViewBoundsToIdealBounds(pulsing_blocks_model_);
 
-  const int page_switcher_height =
-      page_switcher_view_->GetPreferredSize().height();
-  gfx::Rect rect(GetContentsBounds());
-  rect.set_y(rect.bottom() - page_switcher_height);
-  rect.set_height(page_switcher_height);
-  page_switcher_view_->SetBoundsRect(rect);
+  if (page_switcher_view_) {
+    const int page_switcher_height =
+        page_switcher_view_->GetPreferredSize().height();
+    gfx::Rect rect(GetContentsBounds());
+    rect.set_y(rect.bottom() - page_switcher_height);
+    rect.set_height(page_switcher_height);
+    page_switcher_view_->SetBoundsRect(rect);
+  }
 }
 
 bool AppsGridView::OnKeyPressed(const ui::KeyEvent& event) {
@@ -1364,7 +1372,7 @@ void AppsGridView::CalculateDropTarget(const gfx::Point& drag_point,
     current_page = drag_start_page_;
   }
 
-  if (use_page_button_hovering &&
+  if (use_page_button_hovering && page_switcher_view_ &&
       page_switcher_view_->bounds().Contains(point)) {
     gfx::Point page_switcher_point(point);
     views::View::ConvertPointToTarget(this, page_switcher_view_,
@@ -1403,7 +1411,7 @@ void AppsGridView::CalculateDropTargetWithFolderEnabled(
     point = drag_start_grid_view_;
   }
 
-  if (use_page_button_hovering &&
+  if (use_page_button_hovering && page_switcher_view_ &&
       page_switcher_view_->bounds().Contains(point)) {
     gfx::Point page_switcher_point(point);
     views::View::ConvertPointToTarget(this, page_switcher_view_,
@@ -1644,7 +1652,8 @@ void AppsGridView::MaybeStartPageFlipTimer(const gfx::Point& drag_point) {
     StopPageFlipTimer();
   int new_page_flip_target = -1;
 
-  if (page_switcher_view_->bounds().Contains(drag_point)) {
+  if (page_switcher_view_ &&
+      page_switcher_view_->bounds().Contains(drag_point)) {
     gfx::Point page_switcher_point(drag_point);
     views::View::ConvertPointToTarget(this, page_switcher_view_,
                                       &page_switcher_point);