Correcly Report CanEnterMaximizeMode on devices without accelerometers

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 "ash/accelerators/accelerator_controller.h"
 #include "ash/accelerators/accelerator_table.h"
 #include "ash/ash_switches.h"
 #include "ash/display/display_manager.h"
@@ skipping 114 matching lines @@
 }
 
 void MaximizeModeController::AddWindow(aura::Window* window) {
   if (IsMaximizeModeWindowManagerEnabled())
     maximize_mode_window_manager_->AddWindow(window);
 }
 
 #if defined(OS_CHROMEOS)
 void MaximizeModeController::OnAccelerometerUpdated(
     const ui::AccelerometerUpdate& update) {
+  if (!update.has(ui::ACCELEROMETER_SOURCE_SCREEN))
+    return;
+
   bool first_accelerometer_update = !have_seen_accelerometer_data_;
   have_seen_accelerometer_data_ = true;
 
-  if (!update.has(ui::ACCELEROMETER_SOURCE_SCREEN))
-    return;
-
   // Whether or not we enter maximize mode affects whether we handle screen
   // rotation, so determine whether to enter maximize mode first.
   if (!update.has(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD)) {
     if (first_accelerometer_update)
       EnterMaximizeMode();

[flackr, 2015/02/03 22:32:11]

Seems like this path (entering maximize mode when only having a screen
accelerometer) should have been failing and caught by a test but wasn't. Can you
add a test to this effect?

[jonross, 2015/02/04 18:31:23]

Done.

   } else if (chromeos::AccelerometerReader::IsReadingStable(
                  update, ui::ACCELEROMETER_SOURCE_SCREEN) &&
              chromeos::AccelerometerReader::IsReadingStable(
                  update, ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD) &&
              std::abs(update.get(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD)
                           .Length() -
                       update.get(ui::ACCELEROMETER_SOURCE_SCREEN).Length()) <=
                  kNoisyMagnitudeDeviation) {
     // update.has(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD)
     // Ignore the reading if it appears unstable. The reading is considered
@@ skipping 146 matching lines @@
   return elapsed_time <= kLidRecentlyOpenedDuration;
 }
 
 void MaximizeModeController::SetTickClockForTest(
     scoped_ptr<base::TickClock> tick_clock) {
   DCHECK(tick_clock_);
   tick_clock_ = tick_clock.Pass();
 }
 
 }  // namespace ash