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

ash/system/tray/tray_info_label.h

Index: ash/system/tray/tray_info_label.h
diff --git a/ash/system/tray/tray_info_label.h b/ash/system/tray/tray_info_label.h
new file mode 100644
index 0000000000000000000000000000000000000000..d3b6a94a5cfd9cb5dd95252cfdc0390db9d5a941
--- /dev/null
+++ b/ash/system/tray/tray_info_label.h
@@ -0,0 +1,61 @@
+// Copyright (c) 2017 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_INFO_LABEL_H_
+#define ASH_SYSTEM_TRAY_TRAY_INFO_LABEL_H_
+
+#include "ash/system/tray/actionable_view.h"
+#include "ui/views/controls/label.h"
+
+namespace ash {
+
+namespace test {
+class TrayInfoLabelTest;
+}  // namespace test
+
+// A view containing only a label, which is to be inserted as a non-targetable

[Kyle Horimoto, 2017/07/12 22:45:59]

What does non-targetable mean? I Googled it and didn't see any View-related
hits. Can you use a more specific word?

[lesliewatkins, 2017/07/13 22:12:48]

I didn't write that, but based on context, it may no longer be relevant. I'll
just remove the word.

+// 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).
+// InfoLabel can be clickable if it is passed a non-null TrayDetailClickHandler

[Kyle Horimoto, 2017/07/12 22:45:59]

How about "InfoLabel can be clickable; this property is configured by its
delegate."

[Kyle Horimoto, 2017/07/12 22:45:59]

InfoLabel --> TrayInfoLabel, TrayDetailClickHandler -> delegate

[lesliewatkins, 2017/07/13 22:12:47]

Done.

[lesliewatkins, 2017/07/13 22:12:48]

Done.

+// in its constructructor.
+class TrayInfoLabel : public ActionableView {
+ public:
+  // A delegate for handling actions when an InfoLabel is clicked.

[Kyle Horimoto, 2017/07/12 22:45:59]

nit: It does more than just that :)

[lesliewatkins, 2017/07/13 22:12:47]

Changed the wording to reflect that it also determines whether or not a label is
clickable.

+  class Delegate {
+   public:
+    virtual ~Delegate(){};
+    virtual void OnLabelClicked(int message_id) = 0;
+    virtual bool LabelIsClickable(int message_id) = 0;

[Kyle Horimoto, 2017/07/12 22:45:59]

nit: IsLabelClickable() reads better.

[lesliewatkins, 2017/07/13 22:12:48]

Done.

+  };
+
+  // handler can be nullptr, in which case, the InfoLabel will not be

[Kyle Horimoto, 2017/07/12 22:45:59]

handler --> delegate

[Kyle Horimoto, 2017/07/12 22:45:59]

How about "|delegate| may be null, which results in an InfoLabel which cannot be
clicked."

[lesliewatkins, 2017/07/13 22:12:47]

Done.

[lesliewatkins, 2017/07/13 22:12:48]

Done.

+  // clickable. Its status as clickable will be reflected in the style
+  // of the label.
+  TrayInfoLabel(Delegate* delegate, int message_id);
+  ~TrayInfoLabel() override{};
+
+  // Updates the message id, the label text, and the style if the

[Kyle Horimoto, 2017/07/12 22:45:59]

How about: "Updates the InfoLabel to display the message associated with
|message_id|. This may update text styling if the delegate indicates that the
InfoLabel should be clickable."

[lesliewatkins, 2017/07/13 22:12:48]

Done.

+  // InfoLabel changes from clickable to non-clickable (or vice versa).
+  void Update(int message_id);
+
+  // ActionableView:
+  bool PerformAction(const ui::Event& event) override;
+  void GetAccessibleNodeData(ui::AXNodeData* node_data) override;
+
+ private:
+  friend class test::TrayInfoLabelTest;
+
+  bool IsClickable();
+
+  views::Label* const label_;
+  int message_id_;
+
+  Delegate* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrayInfoLabel);
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_TRAY_TRAY_INFO_LABEL_H_