Revert "Speculative revert by sheriff"

ash/content/display/screen_orientation_controller_chromeos.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/content/display/screen_orientation_controller_chromeos.h"
 
 #include "ash/ash_switches.h"
 #include "ash/display/display_info.h"
 #include "ash/display/display_manager.h"
 #include "ash/rotator/screen_rotation_animator.h"
@@ skipping 178 matching lines @@
 }
 
 void ScreenOrientationController::Unlock(content::WebContents* web_contents) {
   aura::Window* requesting_window = web_contents->GetNativeView();
   RemoveLockingWindow(requesting_window);
 }
 
 void ScreenOrientationController::OnDisplayConfigurationChanged() {
   if (ignore_display_configuration_updates_)
     return;
+  DisplayManager* display_manager = Shell::GetInstance()->display_manager();
+  if (!display_manager->HasInternalDisplay())
+    return;
   gfx::Display::Rotation user_rotation =
-      Shell::GetInstance()
-          ->display_manager()
-          ->GetDisplayInfo(gfx::Display::InternalDisplayId())
+      display_manager->GetDisplayInfo(gfx::Display::InternalDisplayId())
           .rotation();
   if (user_rotation != current_rotation_) {
     // A user may change other display configuration settings. When the user
     // does change the rotation setting, then lock rotation to prevent the
     // accelerometer from erasing their change.
     SetRotationLocked(true);
     user_rotation_ = current_rotation_ = user_rotation;
   }
 }
 
 void ScreenOrientationController::OnMaximizeModeStarted() {
   DisplayManager* display_manager = Shell::GetInstance()->display_manager();
-  if (!display_manager->HasInternalDisplay())
-    return;
-  current_rotation_ = user_rotation_ =
-      display_manager->GetDisplayInfo(gfx::Display::InternalDisplayId())
-          .rotation();
+  // Do not exit early, as the internal display can be determined after Maximize
+  // Mode has started. (chrome-os-partner:38796)
+  // Always start observing.
+  if (display_manager->HasInternalDisplay()) {
+    current_rotation_ = user_rotation_ =
+        display_manager->GetDisplayInfo(gfx::Display::InternalDisplayId())
+            .rotation();
+  }
   if (!rotation_locked_)
     LoadDisplayRotationProperties();
   chromeos::AccelerometerReader::GetInstance()->AddObserver(this);
   Shell::GetInstance()->display_controller()->AddObserver(this);
 }
 
 void ScreenOrientationController::OnMaximizeModeEnded() {
-  if (!Shell::GetInstance()->display_manager()->HasInternalDisplay())
-    return;
   chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
   Shell::GetInstance()->display_controller()->RemoveObserver(this);
   if (current_rotation_ != user_rotation_)
     SetDisplayRotation(user_rotation_);
 }
 
 void ScreenOrientationController::LockRotation(
     gfx::Display::Rotation rotation) {
   SetRotationLocked(true);
   SetDisplayRotation(rotation);
@@ skipping 175 matching lines @@
 }
 
 bool ScreenOrientationController::CanRotateInLockedState() {
   return rotation_locked_orientation_ ==
              blink::WebScreenOrientationLockLandscape ||
          rotation_locked_orientation_ ==
              blink::WebScreenOrientationLockPortrait;
 }
 
 }  // namespace ash