Add a row in the network tray to inform users to turn Bluetooth on to enable Tether.

ash/system/tray/tray_details_view.h

 // 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.
 
 #ifndef ASH_SYSTEM_TRAY_TRAY_DETAILS_VIEW_H_
 #define ASH_SYSTEM_TRAY_TRAY_DETAILS_VIEW_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
+#include "ash/system/tray/actionable_view.h"
 #include "ash/system/tray/tray_constants.h"
 #include "ash/system/tray/view_click_listener.h"
 #include "base/macros.h"
 #include "base/timer/timer.h"
 #include "ui/views/controls/button/button.h"
+#include "ui/views/controls/button/label_button.h"
 #include "ui/views/view.h"
 
 namespace gfx {
 struct VectorIcon;
 }  // namespace gfx
 
 namespace views {
 class BoxLayout;
 class CustomButton;
 class Label;
@@ skipping 28 matching lines @@
 
   SystemTrayItem* owner() { return owner_; }
 
  protected:
   // A view containing only a label, which is to be inserted as a non-targetable
   // row within a system menu detailed view (e.g., the "Scanning for devices..."
   // message that can appear at the top of the Bluetooth detailed view).
   class InfoLabel : public View {
    public:
     explicit InfoLabel(int message_id);
-    ~InfoLabel() override;
+    virtual void SetMessage(int message_id) = 0;
 
-    void SetMessage(int message_id);
+    DISALLOW_COPY_AND_ASSIGN(InfoLabel);

[Kyle Horimoto, 2017/07/07 17:33:59]

This should be private.

[lesliewatkins, 2017/07/09 00:57:48]

Done.

+  };
+
+  class InfoLabelNoAction : public InfoLabel {

[Kyle Horimoto, 2017/07/07 17:34:00]

nit: tanderson@ probably has a better idea about UI component naming, but I
wouldn't add "NoAction" to the name. Instead, I'd just call this InfoLabel and
have the extended view's name include something about how this is actionable
(i.e., a button).

[tdanderson, 2017/07/07 21:25:11]

I made a suggestion above that could avoid introducing any new
subclasses. If that doesn't work though, consider if you could have
just two classes:

* InfoLabel (extends View, is non-clickable)
* ClickableInfoLabel (extends InfoLabel, is clickable)

[lesliewatkins, 2017/07/09 00:57:47]

Acknowledged.

+   public:
+    InfoLabelNoAction(int message_id);
+
+    // InfoLabel:
+    void SetMessage(int message_id) override;
 
    private:
     views::Label* const label_;
 
-    DISALLOW_COPY_AND_ASSIGN(InfoLabel);
+    DISALLOW_COPY_AND_ASSIGN(InfoLabelNoAction);
   };
 
+  class InfoLabelEnableBluetooth : public InfoLabel,

[Kyle Horimoto, 2017/07/07 17:33:59]

Does this even need to be an InfoLabel at all? The only virtual function exposed
by InfoLabel is SetMessage(), but the message for this View is never actually
changed since this class is only used to display one message.

+                                   public views::ButtonListener {

[tdanderson, 2017/07/07 21:25:11]

By extending ButtonListener instead of ActionableView, you won't get the
clickable row properties for free: material design "ripple" effect upon clicking
the row, a11y role, etc.

+   public:
+    InfoLabelEnableBluetooth(int message_id);
+
+    // ButtonListener:
+    void ButtonPressed(views::Button* sender, const ui::Event& event) override;
+    // InfoLabel:

[Kyle Horimoto, 2017/07/07 17:34:00]

nit: Newline before this.

+    void SetMessage(int message_id) override;
+
+   private:
+    views::LabelButton* const label_button_;
+
+    DISALLOW_COPY_AND_ASSIGN(InfoLabelEnableBluetooth);
+  };
+
+  // InfoLabel: Factory method

[Kyle Horimoto, 2017/07/07 17:33:59]

nit: Remove this comment and/or change the description to say what it does and
when it should be used.

+  InfoLabel* CreateInfoLabel(int message_id);

[Kyle Horimoto, 2017/07/07 17:33:59]

This should be static.

+
   // views::View:
   void Layout() override;
   int GetHeightForWidth(int width) const override;
 
   // Exposes the layout manager of this view to give control to subclasses.
   views::BoxLayout* box_layout() { return box_layout_; }
 
   // Creates the row containing the back button and title. For material design
   // this appears at the top of the view, for non-material design it appears
   // at the bottom.
@@ skipping 95 matching lines @@
 
   // Used to delay the transition to the default view.
   base::OneShotTimer transition_delay_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayDetailsView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRAY_DETAILS_VIEW_H_