Replace AllAppsTileItemView with ArrowExpandView

ui/app_list/views/start_page_view.cc

Index: ui/app_list/views/start_page_view.cc
diff --git a/ui/app_list/views/start_page_view.cc b/ui/app_list/views/start_page_view.cc
index ed255d7cba6817300533abfc49604fd5e2d5bf5c..f91b0c71b3faf614ee1c942f401efff2417286d0 100644
--- a/ui/app_list/views/start_page_view.cc
+++ b/ui/app_list/views/start_page_view.cc
@@ -23,6 +23,7 @@
 #include "ui/app_list/views/app_list_main_view.h"
 #include "ui/app_list/views/contents_view.h"
 #include "ui/app_list/views/custom_launcher_page_view.h"
+#include "ui/app_list/views/expand_arrow_view.h"
 #include "ui/app_list/views/indicator_chip_view.h"
 #include "ui/app_list/views/search_box_view.h"
 #include "ui/app_list/views/search_result_container_view.h"
@@ -60,7 +61,7 @@ constexpr int kWebViewHeight = 224;
 constexpr int kTileSpacing = 7;
 constexpr int kNumStartPageTilesCols = 5;
 constexpr int kTilesHorizontalMarginLeft = 145;
-constexpr int kCenterColumnOfStartPageAppGrid = 3;
+constexpr int kExpandArrowTopPadding = 28;
 
 constexpr int kLauncherPageBackgroundWidth = 400;
 
@@ -259,21 +260,16 @@ void StartPageView::StartPageTilesContainer::CreateAppsGrid(int apps_num) {
     search_result_tile_views_.emplace_back(tile_item);
   }
 
-  all_apps_button_->UpdateIcon();
-  if (features::IsFullscreenAppListEnabled()) {
-    // Also add a special "all apps" button to the middle of the next row of the
-    // container.
-    tiles_layout_manager->StartRow(0, 0);
-    tiles_layout_manager->SkipColumns(kCenterColumnOfStartPageAppGrid);
-  } else {
+  if (!features::IsFullscreenAppListEnabled()) {
+    all_apps_button_->UpdateIcon();
     // Also add a special "all apps" button to the end of the next row of the
     // container.
     if (i % kNumStartPageTilesCols == 0)
       tiles_layout_manager->StartRow(0, 0);
-  }
 
-  tiles_layout_manager->AddView(all_apps_button_);
-  AddChildView(all_apps_button_);
+    tiles_layout_manager->AddView(all_apps_button_);
+    AddChildView(all_apps_button_);
+  }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -310,6 +306,11 @@ StartPageView::StartPageView(AppListMainView* app_list_main_view,
 
   // The view containing the start page tiles.
   AddChildView(tiles_container_);
+  if (is_fullscreen_app_list_enabled_) {
+    expand_arrow_view_ = new ExpandArrowView(
+        app_list_main_view_->contents_view(), app_list_view);
+    AddChildView(expand_arrow_view_);
+  }
   AddChildView(custom_launcher_page_background_);
 
   tiles_container_->SetResults(view_delegate_->GetModel()->results());
@@ -425,6 +426,19 @@ void StartPageView::Layout() {
   bounds.set_height(tiles_container_->GetHeightForWidth(bounds.width()));
   tiles_container_->SetBoundsRect(bounds);
 
+  if (expand_arrow_view_) {
+    gfx::Rect expand_arrow_rect(bounds);
+    int left_right_padding =
+        (bounds.width() - expand_arrow_view_->GetPreferredSize().width()) / 2;
+
+    expand_arrow_rect.Inset(left_right_padding,
+                            bounds.height() + kExpandArrowTopPadding,
+                            left_right_padding, 0);
+    expand_arrow_rect.set_height(
+        expand_arrow_view_->GetPreferredSize().height());
+    expand_arrow_view_->SetBoundsRect(expand_arrow_rect);
+  }
+
   CustomLauncherPageView* custom_launcher_page_view =
       app_list_main_view_->contents_view()->custom_page_view();
   if (!custom_launcher_page_view)