Flip the flag to enable smooth screen rotation by default.

ash/rotator/screen_rotation_animator_unittest.cc

Index: ash/rotator/screen_rotation_animator_unittest.cc
diff --git a/ash/rotator/screen_rotation_animator_unittest.cc b/ash/rotator/screen_rotation_animator_unittest.cc
index 19de9cebb14f7c317448a2714d58e5395fa80edf..961495d19c04cebdff3a1beaf2b471e03e054f84 100644
--- a/ash/rotator/screen_rotation_animator_unittest.cc
+++ b/ash/rotator/screen_rotation_animator_unittest.cc
@@ -12,6 +12,7 @@
 #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"
@@ -222,6 +223,7 @@ void ScreenRotationAnimatorSmoothAnimationTest::QuitWaitForCopyCallback() {
 
 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) {
@@ -230,8 +232,6 @@ void ScreenRotationAnimatorSmoothAnimationTest::SetUp() {
     return;
   }
 
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kAshEnableSmoothScreenRotation);
   run_loop_ = base::MakeUnique<base::RunLoop>();
   SetScreenRotationAnimator(display_.id(), run_loop_->QuitWhenIdleClosure(),
                             run_loop_->QuitWhenIdleClosure());