Bluetooth API: add discovering changed events

chrome/common/extensions/api/experimental_bluetooth.idl

Index: chrome/common/extensions/api/experimental_bluetooth.idl
diff --git a/chrome/common/extensions/api/experimental_bluetooth.idl b/chrome/common/extensions/api/experimental_bluetooth.idl
index bdfbf814192e09ad76c61a36311bacfc245ba879..13e0ef96d1abbb71fd7b218926949f44e95d5569 100644
--- a/chrome/common/extensions/api/experimental_bluetooth.idl
+++ b/chrome/common/extensions/api/experimental_bluetooth.idl
@@ -212,5 +212,10 @@ namespace experimental.bluetooth {
     // Fired when the power state of bluetooth on the system changes.
     // |powered| : True if bluetooth is powered, false otherwise.
     static void onPowerChanged(boolean has_power);
+
+    // Fired when the discovering state of the system changes.
+    // |discovering| : True if the system is currently in discovery mode, false
+    //                 otherwise.
+    static void onDiscoveringChanged(boolean discovering);
   };
 };