Fix a couple issues with sticky headers

ash/common/system/tray/tray_details_view.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/common/system/tray/tray_details_view.h"
 
 #include "ash/common/ash_view_ids.h"
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/system/tray/fixed_sized_scroll_view.h"
 #include "ash/common/system/tray/system_tray.h"
@@ skipping 25 matching lines @@
 const int kTitleRowSeparatorIndex = 1;
 
 // A view that is used as ScrollView contents. It supports designating some of
 // the children as sticky header rows. The sticky header rows are not scrolled
 // above the top of the visible viewport until the next one "pushes" it up and
 // are painted above other children. To indicate that a child is a sticky header
 // row use set_id(VIEW_ID_STICKY_HEADER).
 class ScrollContentsView : public views::View,
                            public views::ViewTargeterDelegate {
  public:
-  ScrollContentsView() {
+  ScrollContentsView()
+      : box_layout_(new views::BoxLayout(
+            views::BoxLayout::kVertical,
+            0,
+            0,
+            UseMd() ? 0 : kContentsBetweenChildSpacingNonMd)) {
     SetEventTargeter(base::MakeUnique<views::ViewTargeter>(this));
-    SetLayoutManager(
-        new views::BoxLayout(views::BoxLayout::kVertical, 0,
-                             UseMd() ? kContentsVerticalSpacingMd : 0,
-                             UseMd() ? 0 : kContentsBetweenChildSpacingNonMd));
+    SetLayoutManager(box_layout_);
   }
   ~ScrollContentsView() override {}
 
  protected:
   // views::View:
   void OnBoundsChanged(const gfx::Rect& previous_bounds) override {
     PositionHeaderRows();
   }
 
   void PaintChildren(const ui::PaintContext& context) override {
@@ skipping 21 matching lines @@
   }
 
   void ViewHierarchyChanged(
       const ViewHierarchyChangedDetails& details) override {
     if (!details.is_add && details.parent == this) {
       headers_.erase(std::remove_if(headers_.begin(), headers_.end(),
                                     [details](const Header& header) {
                                       return header.view == details.child;
                                     }),
                      headers_.end());
+    } else if (details.is_add && details.parent == this &&
+               details.child == child_at(0)) {
+      // We always want padding on the bottom of the scroll contents.
+      // We only want padding on the top of the scroll contents if the first
+      // child is not a header (in that case, the padding is built into the
+      // header).
+      DCHECK_EQ(box_layout_, GetLayoutManager());
+      box_layout_->set_inside_border_insets(
+          gfx::Insets(details.child->id() == VIEW_ID_STICKY_HEADER
+                          ? 0
+                          : kMenuSeparatorVerticalPadding,
+                      0, kMenuSeparatorVerticalPadding, 0));
     }
   }
 
   // views::ViewTargeterDelegate:
   View* TargetForRect(View* root, const gfx::Rect& rect) override {
     // Give header rows first dibs on events.
     for (auto& header : headers_) {
       views::View* view = header.view;
       gfx::Rect local_to_header = rect;
       local_to_header.Offset(-view->x(), -view->y());
       if (ViewTargeterDelegate::DoesIntersectRect(view, local_to_header))
         return ViewTargeterDelegate::TargetForRect(view, local_to_header);
     }
     return ViewTargeterDelegate::TargetForRect(root, rect);
   }
 
  private:
   const int kSeparatorThickness = 1;
   const SkColor kSeparatorColor = SkColorSetA(SK_ColorBLACK, 0x1F);
   const int kShadowOffsetY = 2;
   const int kShadowBlur = 2;
-  const int kContentsVerticalSpacingMd = 4;
   // TODO(fukino): Remove this constant once we stop maintaining pre-MD design.
   // crbug.com/614453.
   const int kContentsBetweenChildSpacingNonMd = 1;
 
   // A structure that keeps the original offset of each header between the
   // calls to Layout() to allow keeping track of which view should be sticky.
   struct Header {
     explicit Header(views::View* view)
         : view(view), natural_offset(view->y()) {}
 
@@ skipping 65 matching lines @@
     gfx::ShadowValues shadow;
     shadow.emplace_back(gfx::Vector2d(0, kShadowOffsetY), kShadowBlur,
                         kSeparatorColor);
     paint.setLooper(gfx::CreateShadowDrawLooperCorrectBlur(shadow));
     paint.setAntiAlias(true);
     gfx::Rect rect(0, 0, view->width(), view->bounds().bottom());
     canvas->ClipRect(rect, SkRegion::kDifference_Op);
     canvas->DrawRect(rect, paint);
   }
 
+  views::BoxLayout* box_layout_;
+
   // Header child views that stick to the top of visible viewport when scrolled.
   std::vector<Header> headers_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollContentsView);
 };
 
 // Constants for the title row in material design.
 const int kTitleRowVerticalPadding = 4;
 const int kTitleRowProgressBarHeight = 2;
 const int kTitleRowSeparatorHeight = 1;
@@ skipping 241 matching lines @@
     if (index < child_count() - 1 && child_at(index + 1) != title_row_)
       scroll_border_->set_visible(true);
     else
       scroll_border_->set_visible(false);
   }
 
   views::View::OnPaintBorder(canvas);
 }
 
 }  // namespace ash