Add unit test for BluetoothChooserController

chrome/browser/ui/bluetooth/bluetooth_chooser_controller.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/bluetooth/bluetooth_chooser_controller.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 216 matching lines @@
   if (name_it == device_id_to_name_map_.end())
     return;
 
   auto device_it =
       std::find_if(devices_.begin(), devices_.end(),
                    [&device_id](const BluetoothDeviceInfo& device) {
                      return device.id == 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);
     DCHECK(it != device_name_counts_.end());
     DCHECK_GT(it->second, 0);
 
     if (--(it->second) == 0)
       device_name_counts_.erase(it);
 
     device_id_to_name_map_.erase(name_it);
 
     if (view())
-      view()->OnOptionRemoved(device_it - devices_.begin());
+      view()->OnOptionRemoved(index);
   }
 }
 
 void BluetoothChooserController::ResetEventHandler() {
   event_handler_.Reset();
 }
 
 void BluetoothChooserController::ClearAllDevices() {
   devices_.clear();
   device_id_to_name_map_.clear();
   device_name_counts_.clear();
 }