Fix crash in device_sensors.

content/browser/device_sensors/data_fetcher_shared_memory_base.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 "content/browser/device_sensors/data_fetcher_shared_memory_base.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 73 matching lines @@
                   this, &PollingThread::DoPoll);
   }
 }
 
 void DataFetcherSharedMemoryBase::PollingThread::RemoveConsumer(
     ConsumerType consumer_type) {
   DCHECK(fetcher_);
   if (!fetcher_->Stop(consumer_type))
     return;
 
-  consumers_bitmask_ ^= consumer_type;
+  consumers_bitmask_ &= ~consumer_type;
 
   if (!consumers_bitmask_)
     timer_.reset();  // will also stop the timer.
 }
 
 void DataFetcherSharedMemoryBase::PollingThread::DoPoll() {
   DCHECK(fetcher_);
   DCHECK(consumers_bitmask_);
   fetcher_->Fetch(consumers_bitmask_);
 }
@@ skipping 139 matching lines @@
 
 base::MessageLoop* DataFetcherSharedMemoryBase::GetPollingMessageLoop() const {
   return polling_thread_ ? polling_thread_->message_loop() : nullptr;
 }
 
 bool DataFetcherSharedMemoryBase::IsPollingTimerRunningForTesting() const {
   return polling_thread_ ? polling_thread_->IsTimerRunning() : false;
 }
 
 }  // namespace content