Change WebBluetooth chooser OK button's label to be "Pair"

chrome/browser/chooser_controller/chooser_controller.h

Index: chrome/browser/chooser_controller/chooser_controller.h
diff --git a/chrome/browser/chooser_controller/chooser_controller.h b/chrome/browser/chooser_controller/chooser_controller.h
index 161cddd53692bdbe939622a61bb347468409ffff..bb20a77fcbd73ef1048c57eed1c005517428dfa7 100644
--- a/chrome/browser/chooser_controller/chooser_controller.h
+++ b/chrome/browser/chooser_controller/chooser_controller.h
@@ -51,6 +51,9 @@ class ChooserController {
   // Returns the text to be displayed in the chooser title.
   base::string16 GetTitle() const;
 
+  // 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.