[spelling] existance to existence

ash/wm/maximize_mode/maximize_mode_controller.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 "ash/wm/maximize_mode/maximize_mode_controller.h"
 
 #include <utility>
 
 #include "ash/ash_switches.h"
 #include "ash/shell.h"
@@ skipping 100 matching lines @@
       tablet_mode_switch_is_on_(false),
       lid_is_closed_(false),
       scoped_session_observer_(this),
       weak_factory_(this) {
   Shell::Get()->AddShellObserver(this);
   ShellPort::Get()->RecordUserMetricsAction(
       UMA_MAXIMIZE_MODE_INITIALLY_DISABLED);
 
   // TODO(jonross): Do not create MaximizeModeController if the flag is
   // unavailable. This will require refactoring
-  // IsMaximizeModeWindowManagerEnabled to check for the existance of the
+  // IsMaximizeModeWindowManagerEnabled to check for the existence of the
   // controller.
   if (IsEnabled()) {
     ShellPort::Get()->AddDisplayObserver(this);
     chromeos::AccelerometerReader::GetInstance()->AddObserver(this);
   }
   chromeos::PowerManagerClient* power_manager_client =
       chromeos::DBusThreadManager::Get()->GetPowerManagerClient();
   power_manager_client->AddObserver(this);
   power_manager_client->GetSwitchStates(base::Bind(
       &MaximizeModeController::OnGetSwitchStates, weak_factory_.GetWeakPtr()));
@@ skipping 345 matching lines @@
   return elapsed_time.InSeconds() <= kLidRecentlyOpenedDurationSeconds;
 }
 
 void MaximizeModeController::SetTickClockForTest(
     std::unique_ptr<base::TickClock> tick_clock) {
   DCHECK(tick_clock_);
   tick_clock_ = std::move(tick_clock);
 }
 
 }  // namespace ash