Do not enter Maximize Mode while docked

ash/common/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/common/wm/maximize_mode/maximize_mode_controller.h"
 
 #include <utility>
 
 #include "ash/common/ash_switches.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_window_manager.h"
@@ skipping 208 matching lines @@
   if (open)
     last_lid_open_time_ = time;
   lid_is_closed_ = !open;
   LeaveMaximizeMode();
 }
 
 void MaximizeModeController::TabletModeEventReceived(
     bool on,
     const base::TimeTicks& time) {
   tablet_mode_switch_is_on_ = on;
+  // Do not change if docked.
+  if (!display::Display::HasInternalDisplay())
+    return;
   if (on && !IsMaximizeModeWindowManagerEnabled())
     EnterMaximizeMode();
 }
 
 void MaximizeModeController::SuspendImminent() {
   // The system is about to suspend, so record TouchView usage interval metrics
   // based on whether TouchView mode is currently active.
   RecordTouchViewUsageInterval(CurrentTouchViewIntervalType());
 }
 
@@ skipping 113 matching lines @@
 // their original position.
 void MaximizeModeController::OnMaximizeModeEnded() {
   RecordTouchViewUsageInterval(TOUCH_VIEW_INTERVAL_ACTIVE);
 }
 
 void MaximizeModeController::OnDisplayConfigurationChanged() {
   if (!display::Display::HasInternalDisplay() ||
       !WmShell::Get()->IsActiveDisplayId(
           display::Display::InternalDisplayId())) {
     LeaveMaximizeMode();
+  } else if (tablet_mode_switch_is_on_) {

[gwendal, 2017/01/23 20:48:31]

not enough: what if the use is in tent mode, and the tablet_mode_switch_is_on_
has not kicked in yet?

Ok, that's a corner case, but we should check the lid angle as well if
measurable.

[jonross, 2017/01/23 21:08:30]

With the internal display back on we will automatically go back to checking
accelerometer values. This has been how we have been handling exiting docked
mode historically.

The difference is only when tablet_mode_switch_is_on_ as we exit accelerometer
checks while that is true. So right now we wouldn't enter tablet mode.

I can update the docs here to be more explicit, and add a test for both.

+    // The internal display has returned, as we are exiting docked mode.
+    // The device is still in tablet mode, so trigger maximize mode.
+    EnterMaximizeMode();
   }
 }
 
 void MaximizeModeController::RecordTouchViewUsageInterval(
     TouchViewIntervalType type) {
   if (!CanEnterMaximizeMode())
     return;
 
   base::Time current_time = base::Time::Now();
   base::TimeDelta delta = current_time - touchview_usage_interval_start_time_;
@@ skipping 55 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