Display "Restart to update" dialog to Chrome OS users.

ash/common/system/update/tray_update.cc

Index: ash/common/system/update/tray_update.cc
diff --git a/ash/common/system/update/tray_update.cc b/ash/common/system/update/tray_update.cc
index 47e6cc2732e6b57845534ff6a35707dc908b6dcf..7d585199ff42fd677ef30ab8d31995017e6ff381 100644
--- a/ash/common/system/update/tray_update.cc
+++ b/ash/common/system/update/tray_update.cc
@@ -116,6 +116,8 @@ class UpdateView : public ActionableView {
       UpdateStyle();
       SetInkDropMode(InkDropHostView::InkDropMode::ON);
     }
+
+    component_update_required_ = info.component_update_required;
   }
 
   ~UpdateView() override {}
@@ -129,7 +131,8 @@ class UpdateView : public ActionableView {
 
   // Overridden from ActionableView.
   bool PerformAction(const ui::Event& event) override {
-    WmShell::Get()->system_tray_controller()->RequestRestartForUpdate();
+    WmShell::Get()->system_tray_controller()->RequestRestartForUpdate(
+        component_update_required_);
     WmShell::Get()->RecordUserMetricsAction(
         UMA_STATUS_AREA_OS_UPDATE_DEFAULT_SELECTED);
     CloseSystemBubble();
@@ -145,6 +148,7 @@ class UpdateView : public ActionableView {
   }
 
   views::Label* label_;

[James Cook, 2016/11/30 23:01:41]

nit (if you keep this): either label_ = nullptr here or
component_update_required_(false) in constructor for consistency

+  bool component_update_required_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(UpdateView);
 };
@@ -169,7 +173,9 @@ bool TrayUpdate::GetInitialVisibility() {
 views::View* TrayUpdate::CreateDefaultView(LoginStatus status) {
   UpdateInfo info;
   WmShell::Get()->system_tray_delegate()->GetSystemUpdateInfo(&info);
-  return info.update_required ? new UpdateView(this, info) : nullptr;
+  return info.update_required || info.component_update_required
+             ? new UpdateView(this, info)
+             : nullptr;
 }
 
 void TrayUpdate::OnUpdateRecommended(const UpdateInfo& info) {