Live updates for page switcher theming.

Bug: 1139478
Change-Id: I33044e77fde2cc33eeee4395c4129788449aca36
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2618839Reviewed-by: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Yulun Wu <yulunwu@chromium.org>
Commit-Queue: Yulun Wu <yulunwu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842147}

ash/app_list/views/page_switcher.cc

@@ -241,6 +241,16 @@ const char* PageSwitcher::GetClassName() const {
   return "PageSwitcher";
 }
 
+void PageSwitcher::OnThemeChanged() {
+  views::View::OnThemeChanged();
+  if (!buttons_)
+    return;
+  for (auto* child : buttons_->children()) {
+    if (child->GetVisible())
+      child->SchedulePaint();
+  }
+}
+
 void PageSwitcher::OnButtonPressed(views::Button* sender,
                                    const ui::Event& event) {
   if (!model_ || ignore_button_press_)

ash/app_list/views/page_switcher.h

@@ -38,6 +38,7 @@ class PageSwitcher : public views::View,
   gfx::Size CalculatePreferredSize() const override;
   void Layout() override;
   const char* GetClassName() const override;
+  void OnThemeChanged() override;
 
   void set_ignore_button_press(bool ignore) { ignore_button_press_ = ignore; }
   void set_is_tablet_mode(bool started) { is_tablet_mode_ = started; }