Add signal strength indicator icon to WebBluetooth chooser on non-Mac desktops

chrome/browser/chooser_controller/chooser_controller.h

 // Copyright 2016 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 CHROME_BROWSER_CHOOSER_CONTROLLER_CHOOSER_CONTROLLER_H_
 #define CHROME_BROWSER_CHOOSER_CONTROLLER_CHOOSER_CONTROLLER_H_
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 
@@ skipping 44 matching lines @@
     // Called when refreshing options is in progress or complete.
     virtual void OnRefreshStateChanged(bool refreshing) = 0;
 
    protected:
     virtual ~View() {}
   };
 
   // Returns the text to be displayed in the chooser title.
   base::string16 GetTitle() const;
 
+  // Returns if the chooser needs to show an icon before the text.
+  // For WebBluetooth, it is a signal strength icon.
+  virtual bool ShouldShowIconBeforeText() const;
+
   // Returns the text to be displayed in the chooser when there are no options.
   virtual base::string16 GetNoOptionsText() const = 0;
 
   // Returns the label for OK button.
   virtual base::string16 GetOkButtonLabel() const = 0;
 
   // The number of options users can pick from. For example, it can be
   // the number of USB/Bluetooth device names which are listed in the
   // chooser so that users can grant permission.
   virtual size_t NumOptions() const = 0;
 
+  // The signal strength level (0-4 inclusive) of the device at |index|, which
+  // is used to retrieve the corresponding icon to be displayed before the
+  // text. Returns -1 if no icon should be shown.
+  virtual int GetSignalStrengthLevel(size_t index) const;
+
   // The |index|th option string which is listed in the chooser.
   virtual base::string16 GetOption(size_t index) const = 0;
 
   // Refresh the list of options.
   virtual void RefreshOptions() = 0;
 
   // Returns the status text to be shown in the chooser.
   virtual base::string16 GetStatus() const = 0;
 
   // These three functions are called just before this object is destroyed:
@@ skipping 18 matching lines @@
  private:
   content::RenderFrameHost* const owning_frame_;
   const int title_string_id_origin_;
   const int title_string_id_extension_;
   View* view_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(ChooserController);
 };
 
 #endif  // CHROME_BROWSER_CHOOSER_CONTROLLER_CHOOSER_CONTROLLER_H_