2 files changed, 38 insertions, 17 deletions

diff --git a/ui/app_list/views/apps_grid_view.cc b/ui/app_list/views/apps_grid_view.cc
index d2fcb92..dd145ca 100644
--- a/ui/app_list/views/apps_grid_view.cc
+++ b/ui/app_list/views/apps_grid_view.cc
@@ -345,23 +345,23 @@ bool AppsGridView::OnKeyPressed(const ui::KeyEvent& event) {
     const int forward_dir = base::i18n::IsRTL() ? -1 : 1;
     switch (event.key_code()) {
       case ui::VKEY_LEFT:
-        MoveSelected(0, -forward_dir);
+        MoveSelected(0, -forward_dir, 0);
         return true;
       case ui::VKEY_RIGHT:
-        MoveSelected(0, forward_dir);
+        MoveSelected(0, forward_dir, 0);
         return true;
       case ui::VKEY_UP:
-        MoveSelected(0, -cols_);
+        MoveSelected(0, 0, -1);
         return true;
       case ui::VKEY_DOWN:
-        MoveSelected(0, cols_);
+        MoveSelected(0, 0, 1);
         return true;
       case ui::VKEY_PRIOR: {
-        MoveSelected(-1, 0);
+        MoveSelected(-1, 0, 0);
         return true;
       }
       case ui::VKEY_NEXT: {
-        MoveSelected(1, 0);
+        MoveSelected(1, 0, 0);
         return true;
       }
       default:
@@ -492,20 +492,41 @@ views::View* AppsGridView::GetViewAtIndex(const Index& index) const {
   return view_model_.view_at(model_index);
 }
 
-void AppsGridView::MoveSelected(int page_delta, int slot_delta) {
+void AppsGridView::MoveSelected(int page_delta,
+                                int slot_x_delta,
+                                int slot_y_delta) {
   if (!selected_view_)
     return SetSelectedItemByIndex(Index(pagination_model_->selected_page(), 0));
 
   const Index& selected = GetIndexOfView(selected_view_);
-  int target_slot = selected.slot + slot_delta;
-  if (target_slot < 0) {
-    page_delta += (target_slot + 1) / tiles_per_page() - 1;
-    if (selected.page > 0)
-      target_slot = tiles_per_page() + (target_slot + 1) % tiles_per_page() - 1;
-  } else if (target_slot >= tiles_per_page()) {
-    page_delta += target_slot / tiles_per_page();
-    if (selected.page < pagination_model_->total_pages() - 1)
-      target_slot %= tiles_per_page();
+  int target_slot = selected.slot + slot_x_delta + slot_y_delta * cols_;
+
+  if (selected.slot % cols_ == 0 && slot_x_delta == -1) {
+    if (selected.page > 0) {
+      page_delta = -1;
+      target_slot = selected.slot + cols_ - 1;
+    } else {
+      target_slot = selected.slot;
+    }
+  }
+
+  if (selected.slot % cols_ == cols_ - 1 && slot_x_delta == 1) {
+    if (selected.page < pagination_model_->total_pages() - 1) {
+      page_delta = 1;
+      target_slot = selected.slot - cols_ + 1;
+    } else {
+      target_slot = selected.slot;
+    }
+  }
+
+  // Clamp the target slot to the last item if we are moving to the last page
+  // but our target slot is past the end of the item list.
+  if (page_delta &&
+      selected.page + page_delta == pagination_model_->total_pages() - 1) {
+    int last_item_slot = (view_model_.view_size() - 1) % tiles_per_page();
+    if (last_item_slot < target_slot) {
+      target_slot = last_item_slot;
+    }
   }
 
   int target_page = std::min(pagination_model_->total_pages() - 1,
diff --git a/ui/app_list/views/apps_grid_view.h b/ui/app_list/views/apps_grid_view.h
index 4fdf481..8a3f090 100644
--- a/ui/app_list/views/apps_grid_view.h
+++ b/ui/app_list/views/apps_grid_view.h
@@ -147,7 +147,7 @@ class APP_LIST_EXPORT AppsGridView : public views::View,
   Index GetIndexOfView(const views::View* view) const;
   views::View* GetViewAtIndex(const Index& index) const;
 
-  void MoveSelected(int page_delta, int slot_delta);
+  void MoveSelected(int page_delta, int slot_x_delta, int slot_y_delta);
 
   void CalculateIdealBounds();
   void AnimateToIdealBounds();