Revert "Implement scroll shadow on MessageCenterView."

This reverts commit b5cae0bd.

Reason for revert: Settings button and close button on MessageCenterView are missing.

Original change's description:
> Implement scroll shadow on MessageCenterView.
> 
> When MessageCenterView can be scrolled, the 2dp scroll shadow is
> displayed at the bottom.
> 
> The shadow is displayed over notifications on MessageCenterView.
> 
> If MessageCenterView is all scrolled, the shadow is hidden.
> 
> BUG=779880
> 
> Change-Id: I48fdb3e97c57075114ba4210cea40039c295a6d7
> Reviewed-on: https://chromium-review.googlesource.com/923244
> Commit-Queue: Megumi Hattori <megumihattori@google.com>
> Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
> Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#537711}

TBR=yoshiki@chromium.org,tetsui@chromium.org,maajid@chromium.org,megumihattori@google.com

Change-Id: Ib697e58df63ccda943eb4caf920620787bf31577
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 779880
Reviewed-on: https://chromium-review.googlesource.com/925926Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537718}

ash/message_center/message_center_view.cc

@@ -22,13 +22,11 @@
 #include "build/build_config.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/base/l10n/l10n_util.h"
-#include "ui/compositor/paint_recorder.h"
 #include "ui/gfx/animation/slide_animation.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
-#include "ui/gfx/skia_paint_util.h"
 #include "ui/message_center/message_center.h"
 #include "ui/message_center/message_center_types.h"
 #include "ui/message_center/public/cpp/message_center_constants.h"
@@ -64,9 +62,6 @@ namespace {
 constexpr int kMinScrollViewHeight = 77;
 constexpr int kEmptyViewHeight = 96;
 constexpr gfx::Insets kEmptyViewPadding(0, 0, 24, 0);
-constexpr int kScrollShadowOffsetY = -2;
-constexpr int kScrollShadowBlur = 2;
-constexpr SkColor kScrollShadowColor = SkColorSetA(SK_ColorBLACK, 0x24);
 
 void SetViewHierarchyEnabled(views::View* view, bool enabled) {
   for (int i = 0; i < view->child_count(); i++)
@@ -110,8 +105,7 @@ views::View* CreateEmptyNotificationView() {
 
 class MessageCenterScrollView : public views::ScrollView {
  public:
-  MessageCenterScrollView(MessageCenterView* owner) : owner_(owner) {}
-  ~MessageCenterScrollView() override = default;
+  MessageCenterScrollView() = default;
 
  private:
   // views::View:
@@ -121,62 +115,9 @@ class MessageCenterScrollView : public views::ScrollView {
         l10n_util::GetStringUTF16(IDS_ASH_MESSAGE_CENTER_FOOTER_TITLE));
   }
 
-  // views::ScrollBarController:
-  void ScrollToPosition(views::ScrollBar* source, int position) override {
-    views::ScrollView::ScrollToPosition(source, position);
-    owner_->UpdateScrollerShadowVisibility();
-  }
-
-  MessageCenterView* const owner_;
-
   DISALLOW_COPY_AND_ASSIGN(MessageCenterScrollView);
 };
 
-// A view that displays a shadow at the bottom when |scroller_| is bounded.
-class ScrollShadowView : public views::View {
- public:
-  ScrollShadowView(int max_scroll_view_height, int button_height)
-      : max_scroll_view_height_(max_scroll_view_height),
-        button_height_(button_height) {
-    SetPaintToLayer();
-    layer()->SetFillsBoundsOpaquely(false);
-  }
-  ~ScrollShadowView() override = default;
-
- protected:
-  void PaintChildren(const views::PaintInfo& paint_info) override {
-    views::View::PaintChildren(paint_info);
-
-    if (height() != max_scroll_view_height_)
-      return;
-
-    // Draw a shadow at the bottom of the viewport when scrolled.
-    DrawShadow(paint_info.context(),
-               gfx::Rect(0, height(), width(), button_height_));
-  }
-
- private:
-  // Draws a drop shadow above |shadowed_area|.
-  void DrawShadow(const ui::PaintContext& context,
-                  const gfx::Rect& shadowed_area) {
-    ui::PaintRecorder recorder(context, size());
-    gfx::Canvas* canvas = recorder.canvas();
-    cc::PaintFlags flags;
-    gfx::ShadowValues shadow;
-    shadow.emplace_back(gfx::Vector2d(0, kScrollShadowOffsetY),
-                        kScrollShadowBlur, kScrollShadowColor);
-    flags.setLooper(gfx::CreateShadowDrawLooper(shadow));
-    flags.setAntiAlias(true);
-    canvas->ClipRect(shadowed_area, SkClipOp::kDifference);
-    canvas->DrawRect(shadowed_area, flags);
-  }
-
-  const int max_scroll_view_height_;
-  const int button_height_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScrollShadowView);
-};
-
 }  // namespace
 
 // MessageCenterView ///////////////////////////////////////////////////////////
@@ -204,16 +145,12 @@ MessageCenterView::MessageCenterView(
   button_bar_->SetCloseAllButtonEnabled(false);
 
   const int button_height = button_bar_->GetPreferredSize().height();
-  const int max_scroll_view_height = max_height - button_height;
-
-  scroller_shadow_ =
-      new ScrollShadowView(max_scroll_view_height, button_height);
 
-  scroller_ = new MessageCenterScrollView(this);
+  scroller_ = new MessageCenterScrollView();
   // Need to set the transparent background explicitly, since ScrollView has
   // set the default opaque background color.
   scroller_->SetBackgroundColor(SK_ColorTRANSPARENT);
-  scroller_->ClipHeightTo(kMinScrollViewHeight, max_scroll_view_height);
+  scroller_->ClipHeightTo(kMinScrollViewHeight, max_height - button_height);
   scroller_->SetVerticalScrollBar(new views::OverlayScrollBar(false));
   scroller_->SetHorizontalScrollBar(new views::OverlayScrollBar(true));
 
@@ -243,7 +180,6 @@ MessageCenterView::MessageCenterView(
 
   AddChildView(no_notifications_view_);
   AddChildView(scroller_);
-  AddChildView(scroller_shadow_);
   AddChildView(settings_view_);
   AddChildView(button_bar_);
 
@@ -363,13 +299,6 @@ void MessageCenterView::OnDidChangeFocus(views::View* before,
   }
 }
 
-void MessageCenterView::UpdateScrollerShadowVisibility() {
-  // |scroller_shadow_| is visible only if |scroller_| is not all scrolled.
-  scroller_shadow_->SetVisible(scroller_->contents()->height() +
-                                   scroller_->contents()->y() !=
-                               scroller_shadow_->height());
-}
-
 void MessageCenterView::Layout() {
   if (is_closing_)
     return;
@@ -383,7 +312,6 @@ void MessageCenterView::Layout() {
   // TODO(tetsui): Fix the bug above without calling SetBounds, as SetBounds
   // invokes Layout() which is a heavy operation.
   scroller_->SetBounds(0, 0, width(), height() - button_height);
-  scroller_shadow_->SetBounds(0, 0, width(), height() - button_height);
   if (settings_view_->visible()) {
     settings_view_->SetBounds(0, height() - settings_height, width(),
                               settings_height);

ash/message_center/message_center_view.h

@@ -75,8 +75,6 @@ class ASH_EXPORT MessageCenterView
   void OnWillChangeFocus(views::View* before, views::View* now) override {}
   void OnDidChangeFocus(views::View* before, views::View* now) override;
 
-  void UpdateScrollerShadowVisibility();
-
   static const size_t kMaxVisibleNotifications;
 
  protected:
@@ -152,7 +150,6 @@ class ASH_EXPORT MessageCenterView
   // Child views.
   views::ScrollView* scroller_ = nullptr;
   std::unique_ptr<MessageListView> message_list_view_;
-  views::View* scroller_shadow_ = nullptr;
   NotifierSettingsView* settings_view_ = nullptr;
   views::View* no_notifications_view_ = nullptr;
   MessageCenterButtonBar* button_bar_ = nullptr;