Add unit test for BluetoothChooserController

chrome/browser/ui/bluetooth/bluetooth_chooser_controller.cc

Index: chrome/browser/ui/bluetooth/bluetooth_chooser_controller.cc
diff --git a/chrome/browser/ui/bluetooth/bluetooth_chooser_controller.cc b/chrome/browser/ui/bluetooth/bluetooth_chooser_controller.cc
index 7f877bf6f4caab43e47c388910232fd4f8e3417c..14ccb0b25fda411030aacb811b1e4432e0fc98b2 100644
--- a/chrome/browser/ui/bluetooth/bluetooth_chooser_controller.cc
+++ b/chrome/browser/ui/bluetooth/bluetooth_chooser_controller.cc
@@ -234,6 +234,7 @@ void BluetoothChooserController::RemoveDevice(const std::string& device_id) {
                    });
 
   if (device_it != devices_.end()) {
+    size_t index = device_it - devices_.begin();

[Jeffrey Yasskin, 2016/08/26 21:46:12]

Why did this move back?

[juncai, 2016/08/27 00:21:30]

The previous one works in release code, but debug code crashes:
include/c++/4.6/debug/safe_iterator.682:
error: attempt to compute the difference between a singular iterator to a
past-the-end iterator.

include/c++/4.6/debug/safe_iterator.682:
error: attempt to compute the difference between a singular iterator to a
dereferenceable (start-of-sequence) iterator.

And after I changed the code to cache the |index|, it works fine.

[Jeffrey Yasskin, 2016/08/27 00:35:45]

Oops, you're totally right. The .erase() invalidates device_it, so you can't use
it after that point.

[juncai, 2016/08/27 02:15:56]

Acknowledged.

     devices_.erase(device_it);
 
     const auto& it = device_name_counts_.find(name_it->second);
@@ -246,7 +247,7 @@ void BluetoothChooserController::RemoveDevice(const std::string& device_id) {
     device_id_to_name_map_.erase(name_it);
 
     if (view())
-      view()->OnOptionRemoved(device_it - devices_.begin());
+      view()->OnOptionRemoved(index);
   }
 }