DevTools: Fix use-after-free in DevToolsUIBindings::Unsubscribe

chrome/browser/devtools/devtools_ui_bindings.cc

 // Copyright 2014 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/devtools/devtools_ui_bindings.h"
 
 #include "base/command_line.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 578 matching lines @@
     LOG(ERROR) << "Attempt to start unknown event listener " << event_type;
   }
 }
 
 void DevToolsUIBindings::Unsubscribe(const std::string& event_type) {
   if (subscribers_.find(event_type) == subscribers_.end()) {
     LOG(ERROR) << "Not yet subscribed for [" << event_type << "]";
     return;
   }
 
-  subscribers_.erase(event_type);
-
   if (event_type == kDevicesChanged) {
     remote_targets_handler_.reset();
   } else if (event_type == kDeviceCountChanged) {
     EnableRemoteDeviceCounter(false);
   } else {
     LOG(ERROR) << "Attempt to stop unknown event listener " << event_type;
   }
+
+  subscribers_.erase(event_type);
 }
 
 void DevToolsUIBindings::EnableRemoteDeviceCounter(bool enable) {
   DevToolsAndroidBridge* adb_bridge =
       DevToolsAndroidBridge::Factory::GetForProfile(profile_);
   if (!adb_bridge)
     return;
 
   DCHECK(device_listener_enabled_ != enable);
   device_listener_enabled_ = enable;
@@ skipping 187 matching lines @@
                      NULL);
 }
 
 void DevToolsUIBindings::DocumentOnLoadCompletedInMainFrame() {
   // Call delegate first - it seeds importants bit of information.
   delegate_->OnLoadCompleted();
 
   UpdateTheme();
   AddDevToolsExtensionsToClient();
 }