Remove overflow indicator in detailed views.

This CL removes overflow indicator in ScrollView in UnifiedSystemTray's
detailed views. As the corners are rounded, overflow indicator is not
shown properly.

TEST=manual
BUG=835733

Change-Id: I89e7e25a2529a354de9b258ba80697961e1c0745
Reviewed-on: https://chromium-review.googlesource.com/1075912
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562367}

ash/system/ime_menu/ime_menu_tray.cc

@@ -267,6 +267,7 @@ class ImeMenuListView : public ImeListView, public DetailedViewDelegate {
     return native_theme->GetSystemColor(
         ui::NativeTheme::kColorId_BubbleBackground);
   }
+  bool IsOverflowIndicatorEnabled() const override { return true; }
 
  protected:
   void Layout() override {

ash/system/tray/detailed_view_delegate.h

@@ -29,6 +29,9 @@ class DetailedViewDelegate {
 
   // Get the background color of the detailed view.
   virtual SkColor GetBackgroundColor(ui::NativeTheme* native_theme) = 0;
+
+  // Return true if overflow indicator of ScrollView is enabled.
+  virtual bool IsOverflowIndicatorEnabled() const = 0;
 };
 
 }  // namespace ash

ash/system/tray/system_tray_item_detailed_view_delegate.cc

@@ -48,4 +48,8 @@ void SystemTrayItemDetailedViewDelegate::DoTransitionToMainView() {
   owner_->set_restore_focus(false);
 }
 
+bool SystemTrayItemDetailedViewDelegate::IsOverflowIndicatorEnabled() const {
+  return true;
+}
+
 }  // namespace ash

ash/system/tray/system_tray_item_detailed_view_delegate.h

@@ -25,6 +25,7 @@ class ASH_EXPORT SystemTrayItemDetailedViewDelegate
   void TransitionToMainView(bool restore_focus) override;
   void CloseBubble() override;
   SkColor GetBackgroundColor(ui::NativeTheme* native_theme) override;
+  bool IsOverflowIndicatorEnabled() const override;
 
  private:
   // Actually transitions to the main view. The actual transition is

ash/system/tray/tray_detailed_view.cc

@@ -5,7 +5,6 @@
 #include "ash/system/tray/tray_detailed_view.h"
 
 #include "ash/ash_view_ids.h"
-#include "ash/public/cpp/ash_features.h"
 #include "ash/strings/grit/ash_strings.h"
 #include "ash/system/tray/detailed_view_delegate.h"
 #include "ash/system/tray/hover_highlight_view.h"
@@ -306,6 +305,8 @@ void TrayDetailedView::CreateScrollableList() {
   DCHECK(!scroller_);
   scroll_content_ = new ScrollContentsView();
   scroller_ = new views::ScrollView;
+  scroller_->set_draw_overflow_indicator(
+      delegate_->IsOverflowIndicatorEnabled());
   scroller_->SetContents(scroll_content_);
   // TODO(varkha): Make the sticky rows work with EnableViewPortLayer().
   scroller_->SetBackgroundColor(

ash/system/unified/unified_detailed_view_delegate.cc

@@ -27,4 +27,8 @@ SkColor UnifiedDetailedViewDelegate::GetBackgroundColor(
   return SK_ColorTRANSPARENT;
 }
 
+bool UnifiedDetailedViewDelegate::IsOverflowIndicatorEnabled() const {
+  return false;
+}
+
 }  // namespace ash

ash/system/unified/unified_detailed_view_delegate.h

@@ -23,6 +23,7 @@ class UnifiedDetailedViewDelegate : public DetailedViewDelegate {
   void TransitionToMainView(bool restore_focus) override;
   void CloseBubble() override;
   SkColor GetBackgroundColor(ui::NativeTheme* native_theme) override;
+  bool IsOverflowIndicatorEnabled() const override;
 
  private:
   UnifiedSystemTrayController* const tray_controller_;