Add help link when Bluetooth adapter is off for WebBluetooth chooser

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 6e3f69a1a5ea9987a662f14e9f1c613a3042d324..df5f1ab42bb0605a80962beddd1202bcc569e318 100644
--- a/chrome/browser/chooser_controller/chooser_controller.h
+++ b/chrome/browser/chooser_controller/chooser_controller.h
@@ -96,6 +96,9 @@ class ChooserController {
   // Refresh the list of options.
   virtual void RefreshOptions() = 0;
 
+  // Provide help information when the adapter is off.
+  virtual void OpenAdapterOffHelpUrl() const;

[Jeffrey Yasskin, 2016/09/26 23:25:07]

Put this next to the other Open...Url() function. If we want to make it pure,
add a TODO to do that. If not, why not?

[juncai, 2016/09/28 22:45:42]

Since the WebUSB doesn't use this function, and in order to avoid unnecessary
changes to the WebUSB related code, here it is not pure virtual so that WebUSB
code doesn't need to implement it.

Done.

[Jeffrey Yasskin, 2016/09/28 23:12:23]

Sounds good, thanks.

+
   // Returns the status text to be shown in the chooser.
   virtual base::string16 GetStatus() const = 0;