[Scrollable shelf] Fix the issue that app icons are chopped under RTL

When no arrow button shows, the app icons are chopped under RTL. The
reason is that |available_space_| is not adapted to RTL. The issue
is not reproducible under overflow mode. Because in overflow mode,
|available_space_| happens to be the same with the mirrored one.

This CL fixes such an issue by mirroring |available_space_| for the
horizontal shelf under RTL.

Bug: 1016271
Change-Id: I76ec521048b34da9fad97b8d0af6bfd3b8ebb327
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1872800
Commit-Queue: Andrew Xu <andrewxu@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707978}

ash/shelf/scrollable_shelf_view.cc

@@ -576,6 +576,9 @@ void ScrollableShelfView::Layout() {
   const gfx::Insets padding_insets = CalculateEdgePadding();
   available_space_ = GetLocalBounds();
   available_space_.Inset(padding_insets);
+  if (ShouldAdaptToRTL())
+    available_space_ = GetMirroredRect(available_space_);
+
   // The hotseat uses |available_space_| to determine where to show its
   // background, so notify it when it is recalculated.
   GetShelf()->shelf_widget()->hotseat_widget()->UpdateOpaqueBackground();
@@ -1380,6 +1383,13 @@ int ScrollableShelfView::CalculateAdjustedOffset() const {
 }
 
 void ScrollableShelfView::UpdateVisibleSpace() {
+  const bool in_hotseat_tablet =
+      chromeos::switches::ShouldShowShelfHotseat() && IsInTabletMode();
+  if (layout_strategy_ == kNotShowArrowButtons && !in_hotseat_tablet) {
+    visible_space_ = GetLocalBounds();
+    return;
+  }
+
   const int before_padding =
       (left_arrow_->GetVisible() ? kArrowButtonGroupWidth : 0);
   const int after_padding =
@@ -1396,8 +1406,7 @@ void ScrollableShelfView::UpdateVisibleSpace() {
   }
   visible_space_insets -= CalculateRipplePaddingInsets();
 
-  visible_space_ =
-      ShouldAdaptToRTL() ? available_space_ : GetMirroredRect(available_space_);
+  visible_space_ = available_space_;
   visible_space_.Inset(visible_space_insets);
 }
 

ash/shelf/scrollable_shelf_view.h

@@ -311,7 +311,8 @@ class ASH_EXPORT ScrollableShelfView : public views::AccessiblePaneView,
   ScrollArrowView* right_arrow_ = nullptr;
   ShelfContainerView* shelf_container_view_ = nullptr;
 
-  // Available space to accommodate child views.
+  // Available space to accommodate child views. It is mirrored for horizontal
+  // shelf under RTL.
   gfx::Rect available_space_;
 
   // Visible space of |shelf_container_view| in ScrollableShelfView's local