Plumbs touch calibration API to the display manager

chrome/browser/chromeos/display/touch_calibrator/touch_calibrator_controller.cc

 // Copyright 2016 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/chromeos/display/touch_calibrator/touch_calibrator_controller.h"
 
 #include "ash/shell.h"
 #include "ash/touch/touch_transformer_controller.h"
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/chromeos/display/touch_calibrator/touch_calibrator_view.h"
 #include "ui/display/screen.h"
 #include "ui/events/event.h"
 #include "ui/events/event_constants.h"
 
 namespace chromeos {
 
 // Time interval after a touch event during which all other touch events are
 // ignored during calibration.
 const base::TimeDelta TouchCalibratorController::kTouchIntervalThreshold =
     base::TimeDelta::FromMilliseconds(200);
 
 TouchCalibratorController::TouchCalibratorController()
-    : last_touch_timestamp_(base::Time::Now()) {
-  ash::Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
-}
+    : last_touch_timestamp_(base::Time::Now()) {}
 
 TouchCalibratorController::~TouchCalibratorController() {
-  ash::Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
   touch_calibrator_views_.clear();
   StopCalibration();
 }
 
 void TouchCalibratorController::OnDisplayConfigurationChanged() {
   touch_calibrator_views_.clear();
   StopCalibration();
 }
 
 void TouchCalibratorController::StartCalibration(
     const display::Display& target_display) {
   is_calibrating_ = true;
+  ash::Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
   target_display_ = target_display;
 
   // Clear all touch calibrator views used in any previous calibration.
   touch_calibrator_views_.clear();
 
   // Reset the calibration data.
   touch_point_quad_.fill(std::make_pair(gfx::Point(0, 0), gfx::Point(0, 0)));
 
   std::vector<display::Display> displays =
       display::Screen::GetScreen()->GetAllDisplays();
 
   for (const display::Display& display : displays) {
     bool is_primary_view = display.id() == target_display_.id();
     touch_calibrator_views_[display.id()] =
         base::MakeUnique<TouchCalibratorView>(display, is_primary_view);
   }
 
   // TODO(malaykeshav): Call TouchTransformerController::SetForCalibration()
 
   // Add self as an event handler target.
   ash::Shell::GetInstance()->AddPreTargetHandler(this);
 }
 
 void TouchCalibratorController::StopCalibration() {
   if (!is_calibrating_)
     return;
   is_calibrating_ = false;
+  ash::Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
 
   // TODO(malaykeshav): Call TouchTransformerController::SetForCalibration()
 
   // Remove self as the event handler.
   ash::Shell::GetInstance()->RemovePreTargetHandler(this);
 
   // Transition all touch calibrator views to their final state for a graceful
   // exit.
   for (const auto& it : touch_calibrator_views_)
     it.second->SkipToFinalState();
@@ skipping 59 matching lines @@
         target_display_.id(), touch_point_quad_,
         target_screen_calibration_view->size());
     StopCalibration();
     return;
   }
 
   target_screen_calibration_view->AdvanceToNextState();
 }
 
 }  // namespace chromeos