Bluetooth API: improve discovery

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 13e0ef96d1abbb71fd7b218926949f44e95d5569..a95c4b713d2debd88e6d4ec2fe3a6660804b03f1 100644
--- a/chrome/common/extensions/api/experimental_bluetooth.idl
+++ b/chrome/common/extensions/api/experimental_bluetooth.idl
@@ -190,8 +190,9 @@ namespace experimental.bluetooth {
                                         optional ResultCallback callback);
 
     // Start discovery. Discovered devices will be returned via the
-    // |onDeviceDiscovered| callback. Note that discovery can be resource
-    // intensive. stopDiscovery should be called as soon as is convenient.
+    // |onDeviceDiscovered| callback.  Discovery will fail to start if it is
+    // already in progress.  Discovery can be resource intensive: stopDiscovery
+    // should be called as soon as possible.
     // |options|  : The options for this function.
     // |callback| : Called to indicate success or failure.
     static void startDiscovery(