Relayout on battery status change.

A child label of BatteryView can change their visibility and size.
Also, EnterpriseManagedView can change its visibility.
We have to explicitly call Layout() in ChildPreferredSizeChanged() &
ChildVisibilityChanged().

TEST=manual (connect/disconnect power cable while opening the tray)
BUG=none

Change-Id: Ia1c16669bcdce0740510b7c255642d7985763225
Reviewed-on: https://chromium-review.googlesource.com/959944Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543644}

ash/system/unified/unified_system_info_view.cc

@@ -100,6 +100,10 @@ class BatteryView : public views::View, public PowerStatus::Observer {
   BatteryView();
   ~BatteryView() override;
 
+  // views::View:
+  void ChildPreferredSizeChanged(views::View* child) override;
+  void ChildVisibilityChanged(views::View* child) override;
+
   // PowerStatus::Observer:
   void OnPowerStatusChanged() override;
 
@@ -142,6 +146,14 @@ BatteryView::~BatteryView() {
   PowerStatus::Get()->RemoveObserver(this);
 }
 
+void BatteryView::ChildPreferredSizeChanged(views::View* child) {
+  PreferredSizeChanged();
+}
+
+void BatteryView::ChildVisibilityChanged(views::View* child) {
+  PreferredSizeChanged();
+}
+
 void BatteryView::OnPowerStatusChanged() {
   Update();
 }
@@ -270,4 +282,12 @@ UnifiedSystemInfoView::UnifiedSystemInfoView()
 
 UnifiedSystemInfoView::~UnifiedSystemInfoView() = default;
 
+void UnifiedSystemInfoView::ChildVisibilityChanged(views::View* child) {
+  Layout();
+}
+
+void UnifiedSystemInfoView::ChildPreferredSizeChanged(views::View* child) {
+  Layout();
+}
+
 }  // namespace ash

ash/system/unified/unified_system_info_view.h

@@ -18,6 +18,10 @@ class ASH_EXPORT UnifiedSystemInfoView : public views::View {
   UnifiedSystemInfoView();
   ~UnifiedSystemInfoView() override;
 
+  // views::View:
+  void ChildPreferredSizeChanged(views::View* child) override;
+  void ChildVisibilityChanged(views::View* child) override;
+
  private:
   FRIEND_TEST_ALL_PREFIXES(UnifiedSystemInfoViewTest, EnterpriseManagedVisible);
   FRIEND_TEST_ALL_PREFIXES(UnifiedSystemInfoViewTest,