Require at least a 25 degree rise angle before changing screen rotation.

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/accelerometer/accelerometer_controller.h"
 #include "ash/ash_switches.h"
@@ skipping 42 matching lines @@
 // attached to the same physical device and so should be under the same
 // acceleration.
 const float kNoisyMagnitudeDeviation = 0.1f;
 
 // The angle which the screen has to be rotated past before the display will
 // rotate to match it (i.e. 45.0f is no stickiness).
 const float kDisplayRotationStickyAngleDegrees = 60.0f;
 
 // The minimum acceleration in a direction required to trigger screen rotation.
 // This prevents rapid toggling of rotation when the device is near flat and
-// there is very little screen aligned force on it.
-const float kMinimumAccelerationScreenRotation = 0.3f;
+// there is very little screen aligned force on it. The value is effectively the
+// sine of the rise angle required, with the current value requiring at least a
+// 25 degree rise.
+const float kMinimumAccelerationScreenRotation = 0.42f;
 
 const float kRadiansToDegrees = 180.0f / 3.14159265f;
 
 // Returns the angle between |base| and |other| in degrees.
 float AngleBetweenVectorsInDegrees(const gfx::Vector3dF& base,
                                  const gfx::Vector3dF& other) {
   return acos(gfx::DotProduct(base, other) /
               base.Length() / other.Length()) * kRadiansToDegrees;
 }
 
@@ skipping 229 matching lines @@
 void MaximizeModeController::SetDisplayRotation(
     DisplayManager* display_manager,
     gfx::Display::Rotation rotation) {
   base::AutoReset<bool> auto_in_set_screen_rotation(
       &in_set_screen_rotation_, true);
   display_manager->SetDisplayRotation(gfx::Display::InternalDisplayId(),
                                       rotation);
 }
 
 }  // namespace ash