Flip the flag to enable smooth screen rotation by default.

ash/rotator/screen_rotation_animator_unittest.cc

 // Copyright 2017 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/rotator/screen_rotation_animator.h"
 
 #include "ash/ash_switches.h"
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/public/cpp/config.h"
 #include "ash/rotator/screen_rotation_animator_observer.h"
 #include "ash/rotator/test/screen_rotation_animator_test_api.h"
 #include "ash/shell.h"
 #include "ash/shell_port.h"
 #include "ash/test/ash_test_base.h"
+#include "ash/test/ash_test_helper.h"
 #include "base/callback_forward.h"
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "base/run_loop.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
 #include "ui/compositor/scoped_animation_duration_scale_mode.h"
 #include "ui/display/display.h"
 #include "ui/display/manager/display_manager.h"
 #include "ui/display/screen.h"
@@ skipping 190 matching lines @@
   UpdateDisplay(specs);
   QuitWaitForCopyCallback();
 }
 
 void ScreenRotationAnimatorSmoothAnimationTest::QuitWaitForCopyCallback() {
   run_loop_->QuitWhenIdle();
 }
 
 void ScreenRotationAnimatorSmoothAnimationTest::SetUp() {
   AshTestBase::SetUp();
+  ash_test_helper()->reset_commandline();

[oshima, 2017/04/25 23:36:01]

Since resetting itself doesn't change the value obtained from the command line,
this may not be intuitive.

Can you add comment that this works because you (re)create a
ScreenRotationAnimator below?

[wutao, 2017/04/26 01:05:34]

Comments added.

 
   display_ = display::Screen::GetScreen()->GetPrimaryDisplay();
   if (Shell::GetAshConfig() == Config::MASH) {
     ASSERT_TRUE(ShellPort::Get()->GetDisplayInfo(display_id()).id() !=
                 display_id());
     return;
   }
 
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kAshEnableSmoothScreenRotation);
   run_loop_ = base::MakeUnique<base::RunLoop>();
   SetScreenRotationAnimator(display_.id(), run_loop_->QuitWhenIdleClosure(),
                             run_loop_->QuitWhenIdleClosure());
   non_zero_duration_mode_ =
       base::MakeUnique<ui::ScopedAnimationDurationScaleMode>(
           ui::ScopedAnimationDurationScaleMode::SLOW_DURATION);
 }
 
 void ScreenRotationAnimatorSmoothAnimationTest::SetScreenRotationAnimator(
     int64_t display_id,
@@ skipping 289 matching lines @@
   SetDisplayRotation(display_manager()->GetDisplayAt(1).id(),
                      display::Display::ROTATE_0);
   animator()->Rotate(display::Display::ROTATE_90,
                      display::Display::RotationSource::ROTATION_SOURCE_USER);
   WaitForCopyCallback();
   EXPECT_EQ(1U, display_manager()->GetNumDisplays());
   EXPECT_EQ(secondary_display_id, display_manager()->GetDisplayAt(0).id());
 }
 
 }  // namespace ash