Reset Bluetooth EventHandler when it is invalid

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 "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/net/referrer.h"
 #include "chrome/browser/profiles/profile_manager.h"
@@ skipping 47 matching lines @@
   const auto& it = device_name_map_.find(device_name);
   DCHECK(it != device_name_map_.end());
   return it->second == 1
              ? device_name
              : l10n_util::GetStringFUTF16(
                    IDS_DEVICE_CHOOSER_DEVICE_NAME_WITH_ID, device_name,
                    base::UTF8ToUTF16(device_names_and_ids_[index].second));
 }
 
 void BluetoothChooserController::RefreshOptions() {
+  if (event_handler_.is_null())
+    return;
   ClearAllDevices();
   event_handler_.Run(content::BluetoothChooser::Event::RESCAN, std::string());
 }
 
 base::string16 BluetoothChooserController::GetStatus() const {
   return status_text_;
 }
 
 void BluetoothChooserController::Select(size_t index) {
+  if (event_handler_.is_null())

[Jeffrey Yasskin, 2016/08/05 20:37:51]

Would it make sense to record how often this happens to UMA? Each time it does
is probably a confusing user experience (since their selection didn't take
effect), so we'd like to fix it, and when the numbers reach 0, we can turn this
into a DCHECK.

[juncai, 2016/08/05 22:51:58]

Done.

+    return;
   DCHECK_LT(index, device_names_and_ids_.size());
   event_handler_.Run(content::BluetoothChooser::Event::SELECTED,
                      device_names_and_ids_[index].second);
 }
 
 void BluetoothChooserController::Cancel() {
+  if (event_handler_.is_null())
+    return;
   event_handler_.Run(content::BluetoothChooser::Event::CANCELLED,
                      std::string());
 }
 
 void BluetoothChooserController::Close() {
+  if (event_handler_.is_null())
+    return;
   event_handler_.Run(content::BluetoothChooser::Event::CANCELLED,
                      std::string());
 }
 
 void BluetoothChooserController::OpenHelpCenterUrl() const {
   GetBrowser()->OpenURL(content::OpenURLParams(
       GURL(chrome::kChooserBluetoothOverviewURL), content::Referrer(),
       NEW_FOREGROUND_TAB, ui::PAGE_TRANSITION_AUTO_TOPLEVEL,
       false /* is_renderer_initialized */));
 }
@@ skipping 67 matching lines @@
       if (--device_name_map_[it->first] == 0)
         device_name_map_.erase(it->first);
       device_names_and_ids_.erase(it);
       if (view())
         view()->OnOptionRemoved(index);
       return;
     }
   }
 }
 
+void BluetoothChooserController::ResetEventHandler() {
+  event_handler_.Reset();
+}
+
 void BluetoothChooserController::ClearAllDevices() {
   device_names_and_ids_.clear();
   device_name_map_.clear();
 }