Use standardized and extendable accelerometer update type.

Updates the type used when delivering accelerometer updates in ash to:
- support a variable number of accelerometers
- be measured in m/s^2
- use axes consistent with the web device motion API.

BUG=380831
TEST=MaximizeModeController unit tests still pass.
TEST=Run on a touchview device and verify that entering / exiting touchview as well as screen rotation still works.

Review URL: https://codereview.chromium.org/500613003

Cr-Commit-Position: refs/heads/master@{#292968}

ash/BUILD.gn

@@ -29,6 +29,7 @@ component("ash") {
     "//net",
     "//skia",
     "//third_party/icu",
+    "//ui/accelerometer",
     "//ui/accessibility",
     "//ui/app_list",
     "//ui/aura",
@@ -251,6 +252,7 @@ test("ash_unittests") {
     "//skia",
     "//testing/gtest",
     "//third_party/icu",
+    "//ui/accelerometer",
     "//ui/accessibility",
     "//ui/aura",
     "//ui/aura:test_support",

ash/accelerometer/accelerometer_controller.cc

@@ -5,7 +5,6 @@
 #include "ash/accelerometer/accelerometer_controller.h"
 
 #include "ash/accelerometer/accelerometer_observer.h"
-#include "ui/gfx/geometry/vector3d_f.h"
 
 namespace ash {
 
@@ -31,11 +30,10 @@ void AccelerometerController::RemoveObserver(AccelerometerObserver* observer) {
 }
 
 #if defined(OS_CHROMEOS)
-void AccelerometerController::HandleAccelerometerReading(
-    const gfx::Vector3dF& base,
-    const gfx::Vector3dF& lid) {
+void AccelerometerController::HandleAccelerometerUpdate(
+    const ui::AccelerometerUpdate& update) {
   FOR_EACH_OBSERVER(AccelerometerObserver, observers_,
-      OnAccelerometerUpdated(base, lid));
+      OnAccelerometerUpdated(update));
 }
 #endif
 

ash/accelerometer/accelerometer_controller.h

@@ -18,10 +18,6 @@ namespace base {
 class TaskRunner;
 }
 
-namespace gfx {
-class Vector3dF;
-}
-
 namespace ash {
 
 class AccelerometerObserver;
@@ -50,8 +46,8 @@ class ASH_EXPORT AccelerometerController
   // This needs to be CHROMEOS only as on other platforms it does not actually
   // override a method.
   // chromeos::AccelerometerReader::Delegate:
-  virtual void HandleAccelerometerReading(const gfx::Vector3dF& base,
-                                          const gfx::Vector3dF& lid) OVERRIDE;
+  virtual void HandleAccelerometerUpdate(
+      const ui::AccelerometerUpdate& update) OVERRIDE;
 #endif
 
  private:

ash/accelerometer/accelerometer_observer.h

@@ -6,20 +6,17 @@
 #define ASH_ACCELEROMETER_ACCELEROMETER_OBSERVER_H_
 
 #include "ash/ash_export.h"
-
-namespace gfx {
-class Vector3dF;
-}
+#include "ui/accelerometer/accelerometer_types.h"
 
 namespace ash {
 
 // The interface for classes which observe accelerometer updates.
 class ASH_EXPORT AccelerometerObserver {
  public:
-  // Invoked when an accelerometer reading has been taken. The |base| and |lid|
-  // accelerometer readings are in G's.
-  virtual void OnAccelerometerUpdated(const gfx::Vector3dF& base,
-                                      const gfx::Vector3dF& lid) = 0;
+  // Invoked when an accelerometer reading has been taken. The |update| can
+  // contain readings from one or more AccelerometerSources.
+  virtual void OnAccelerometerUpdated(
+      const ui::AccelerometerUpdate& update) = 0;
 
  protected:
   virtual ~AccelerometerObserver() {}

ash/ash.gyp

@@ -894,6 +894,7 @@
         '../skia/skia.gyp:skia',
         '../third_party/icu/icu.gyp:icui18n',
         '../third_party/icu/icu.gyp:icuuc',
+        '../ui/accelerometer/ui_accelerometer.gyp:ui_accelerometer',
         '../ui/accessibility/accessibility.gyp:accessibility',
         '../ui/app_list/app_list.gyp:app_list',
         '../ui/aura/aura.gyp:aura',
@@ -1065,6 +1066,7 @@
         '../testing/gtest.gyp:gtest',
         '../third_party/icu/icu.gyp:icui18n',
         '../third_party/icu/icu.gyp:icuuc',
+        '../ui/accelerometer/ui_accelerometer.gyp:ui_accelerometer',
         '../ui/accessibility/accessibility.gyp:accessibility',
         '../ui/app_list/app_list.gyp:app_list',
         '../ui/aura/aura.gyp:aura',

ash/wm/maximize_mode/maximize_mode_controller.cc

@@ -56,34 +56,37 @@ const float kMaxStableAngle = 340.0f;
 const base::TimeDelta kLidRecentlyOpenedDuration =
     base::TimeDelta::FromSeconds(2);
 
+// The mean acceleration due to gravity on Earth in m/s^2.
+const float kMeanGravity = 9.80665f;
+
 // When the device approaches vertical orientation (i.e. portrait orientation)
 // the accelerometers for the base and lid approach the same values (i.e.
 // gravity pointing in the direction of the hinge). When this happens we cannot
 // compute the hinge angle reliably and must turn ignore accelerometer readings.
 // This is the minimum acceleration perpendicular to the hinge under which to
-// detect hinge angle.
-const float kHingeAngleDetectionThreshold = 0.25f;
+// detect hinge angle in m/s^2.
+const float kHingeAngleDetectionThreshold = 2.5f;
 
 // The maximum deviation from the acceleration expected due to gravity under
-// which to detect hinge angle and screen rotation.
-const float kDeviationFromGravityThreshold = 0.1f;
+// which to detect hinge angle and screen rotation in m/s^2
+const float kDeviationFromGravityThreshold = 1.0f;
 
 // The maximum deviation between the magnitude of the two accelerometers under
-// which to detect hinge angle and screen rotation. These accelerometers are
-// attached to the same physical device and so should be under the same
-// acceleration.
-const float kNoisyMagnitudeDeviation = 0.1f;
+// which to detect hinge angle and screen rotation in m/s^2. These
+// accelerometers are attached to the same physical device and so should be
+// under the same acceleration.
+const float kNoisyMagnitudeDeviation = 1.0f;
 
 // 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. 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;
+// The minimum acceleration in m/s^2 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. The value is
+// effectively the sine of the rise angle required times the acceleration due
+// to gravity, with the current value requiring at least a 25 degree rise.
+const float kMinimumAccelerationScreenRotation = 4.2f;
 
 const float kRadiansToDegrees = 180.0f / 3.14159265f;
 
@@ -236,26 +239,35 @@ void MaximizeModeController::Shutdown() {
 }
 
 void MaximizeModeController::OnAccelerometerUpdated(
-    const gfx::Vector3dF& base,
-    const gfx::Vector3dF& lid) {
+    const ui::AccelerometerUpdate& update) {
   bool first_accelerometer_update = !have_seen_accelerometer_data_;
   have_seen_accelerometer_data_ = true;
 
   // Ignore the reading if it appears unstable. The reading is considered
   // unstable if it deviates too much from gravity and/or the magnitude of the
   // reading from the lid differs too much from the reading from the base.
-  float base_magnitude = base.Length();
-  float lid_magnitude = lid.Length();
-  if (std::abs(base_magnitude - lid_magnitude) > kNoisyMagnitudeDeviation ||
-      std::abs(base_magnitude - 1.0f) > kDeviationFromGravityThreshold ||
-      std::abs(lid_magnitude - 1.0f) > kDeviationFromGravityThreshold) {
-      return;
+  float base_magnitude =
+      update.has(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD) ?
+      update.get(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD).Length() :
+      0.0f;
+  float lid_magnitude = update.has(ui::ACCELEROMETER_SOURCE_SCREEN) ?
+      update.get(ui::ACCELEROMETER_SOURCE_SCREEN).Length() : 0.0f;
+  bool lid_stable = update.has(ui::ACCELEROMETER_SOURCE_SCREEN) &&
+      std::abs(lid_magnitude - kMeanGravity) <= kDeviationFromGravityThreshold;
+  bool base_angle_stable = lid_stable &&
+      update.has(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD) &&
+      std::abs(base_magnitude - lid_magnitude) <= kNoisyMagnitudeDeviation &&
+      std::abs(base_magnitude - kMeanGravity) <= kDeviationFromGravityThreshold;
+
+  if (base_angle_stable) {
+    // Responding to the hinge rotation can change the maximize mode state which
+    // affects screen rotation, so we handle hinge rotation first.
+    HandleHingeRotation(
+        update.get(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD),
+        update.get(ui::ACCELEROMETER_SOURCE_SCREEN));
   }
-
-  // Responding to the hinge rotation can change the maximize mode state which
-  // affects screen rotation, so we handle hinge rotation first.
-  HandleHingeRotation(base, lid);
-  HandleScreenRotation(lid);
+  if (lid_stable)
+    HandleScreenRotation(update.get(ui::ACCELEROMETER_SOURCE_SCREEN));
 
   if (first_accelerometer_update) {
     // On the first accelerometer update we will know if we have entered
@@ -303,14 +315,14 @@ void MaximizeModeController::SuspendDone(
 
 void MaximizeModeController::HandleHingeRotation(const gfx::Vector3dF& base,
                                                  const gfx::Vector3dF& lid) {
-  static const gfx::Vector3dF hinge_vector(0.0f, 1.0f, 0.0f);
+  static const gfx::Vector3dF hinge_vector(1.0f, 0.0f, 0.0f);
   bool maximize_mode_engaged = IsMaximizeModeWindowManagerEnabled();
   // Ignore the component of acceleration parallel to the hinge for the purposes
   // of hinge angle calculation.
   gfx::Vector3dF base_flattened(base);
   gfx::Vector3dF lid_flattened(lid);
-  base_flattened.set_y(0.0f);
-  lid_flattened.set_y(0.0f);
+  base_flattened.set_x(0.0f);
+  lid_flattened.set_x(0.0f);
 
   // As the hinge approaches a vertical angle, the base and lid accelerometers
   // approach the same values making any angle calculations highly inaccurate.
@@ -321,10 +333,13 @@ void MaximizeModeController::HandleHingeRotation(const gfx::Vector3dF& base,
   }
 
   // Compute the angle between the base and the lid.
-  float angle = ClockwiseAngleBetweenVectorsInDegrees(base_flattened,
-      lid_flattened, hinge_vector);
+  float lid_angle = 180.0f - ClockwiseAngleBetweenVectorsInDegrees(
+      base_flattened, lid_flattened, hinge_vector);
+  if (lid_angle < 0.0f)
+    lid_angle += 360.0f;
 
-  bool is_angle_stable = angle > kMinStableAngle && angle < kMaxStableAngle;
+  bool is_angle_stable = lid_angle >= kMinStableAngle &&
+                         lid_angle <= kMaxStableAngle;
 
   // Clear the last_lid_open_time_ for a stable reading so that there is less
   // chance of a delay if the lid is moved from the close state to the fully
@@ -337,10 +352,10 @@ void MaximizeModeController::HandleHingeRotation(const gfx::Vector3dF& base,
   // such that observations of state changes occur after the change and shell
   // has fewer states to track.
   if (maximize_mode_engaged && is_angle_stable &&
-      angle < kExitMaximizeModeAngle) {
+      lid_angle <= kExitMaximizeModeAngle) {
     LeaveMaximizeMode();
   } else if (!lid_is_closed_ && !maximize_mode_engaged &&
-             angle > kEnterMaximizeModeAngle &&
+             lid_angle >= kEnterMaximizeModeAngle &&
              (is_angle_stable || !WasLidOpenedRecently())) {
     EnterMaximizeMode();
   }
@@ -372,7 +387,7 @@ void MaximizeModeController::HandleScreenRotation(const gfx::Vector3dF& lid) {
   // The reference vector is the angle of gravity when the device is rotated
   // clockwise by 45 degrees. Computing the angle between this vector and
   // gravity we can easily determine the expected display rotation.
-  static gfx::Vector3dF rotation_reference(-1.0f, 1.0f, 0.0f);
+  static const gfx::Vector3dF rotation_reference(-1.0f, -1.0f, 0.0f);
 
   // Set the down vector to match the expected direction of gravity given the
   // last configured rotation. This is used to enforce a stickiness that the
@@ -380,13 +395,13 @@ void MaximizeModeController::HandleScreenRotation(const gfx::Vector3dF& lid) {
   // when holding the device near 45 degrees.
   gfx::Vector3dF down(0.0f, 0.0f, 0.0f);
   if (current_rotation == gfx::Display::ROTATE_0)
-    down.set_x(-1.0f);
+    down.set_y(-1.0f);
   else if (current_rotation == gfx::Display::ROTATE_90)
-    down.set_y(1.0f);
+    down.set_x(-1.0f);
   else if (current_rotation == gfx::Display::ROTATE_180)
-    down.set_x(1.0f);
+    down.set_y(1.0f);
   else
-    down.set_y(-1.0f);
+    down.set_x(1.0f);
 
   // Don't rotate if the screen has not passed the threshold.
   if (AngleBetweenVectorsInDegrees(down, lid_flattened) <

ash/wm/maximize_mode/maximize_mode_controller.h

@@ -109,8 +109,8 @@ class ASH_EXPORT MaximizeModeController
   void Shutdown();
 
   // AccelerometerObserver:
-  virtual void OnAccelerometerUpdated(const gfx::Vector3dF& base,
-                                      const gfx::Vector3dF& lid) OVERRIDE;
+  virtual void OnAccelerometerUpdated(
+      const ui::AccelerometerUpdate& update) OVERRIDE;
 
   // ShellObserver:
   virtual void OnAppTerminating() OVERRIDE;

chrome/browser/chromeos/display/display_preferences_unittest.cc

@@ -38,6 +38,9 @@ const char kMirroredKey[] = "mirrored";
 const char kPositionKey[] = "position";
 const char kOffsetKey[] = "offset";
 
+// The mean acceleration due to gravity on Earth in m/s^2.
+const float kMeanGravity = 9.80665f;
+
 class DisplayPreferencesTest : public ash::test::AshTestBase {
  protected:
   DisplayPreferencesTest()
@@ -663,13 +666,20 @@ TEST_F(DisplayPreferencesTest, DontSaveMaximizeModeControllerRotations) {
                                       gfx::Display::ROTATE_0);
 
   // Open up 270 degrees to trigger maximize mode
-  controller->OnAccelerometerUpdated(gfx::Vector3dF(0.0f, 0.0f, -1.0f),
-                                     gfx::Vector3dF(-1.0f, 0.0f, 0.0f));
+  ui::AccelerometerUpdate update;
+  update.Set(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD,
+             0.0f, 0.0f, kMeanGravity);
+  update.Set(ui::ACCELEROMETER_SOURCE_SCREEN,
+             0.0f, -kMeanGravity, 0.0f);
+  controller->OnAccelerometerUpdated(update);
   EXPECT_TRUE(controller->IsMaximizeModeWindowManagerEnabled());
 
   // Trigger 90 degree rotation
-  controller->OnAccelerometerUpdated(gfx::Vector3dF(0.0f, 1.0f, 0.0f),
-                                     gfx::Vector3dF(0.0f, 1.0f, 0.0f));
+  update.Set(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD,
+             -kMeanGravity, 0.0f, 0.0f);
+  update.Set(ui::ACCELEROMETER_SOURCE_SCREEN,
+             -kMeanGravity, 0.0f, 0.0f);
+  controller->OnAccelerometerUpdated(update);
   EXPECT_EQ(gfx::Display::ROTATE_90, display_manager->
                 GetDisplayInfo(gfx::Display::InternalDisplayId()).rotation());
 
@@ -799,9 +809,12 @@ TEST_F(DisplayPreferencesTest, LoadRotationNoLogin) {
   EXPECT_EQ(gfx::Display::ROTATE_0, before_maximize_mode_rotation);
 
   // Open up 270 degrees to trigger maximize mode
-  maximize_mode_controller->
-      OnAccelerometerUpdated(gfx::Vector3dF(0.0f, 0.0f, -1.0f),
-                             gfx::Vector3dF(-1.0f, 0.0f, 0.0f));
+  ui::AccelerometerUpdate update;
+  update.Set(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD,
+             0.0f, 0.0f, kMeanGravity);
+  update.Set(ui::ACCELEROMETER_SOURCE_SCREEN,
+             0.0f, -kMeanGravity, 0.0f);
+  maximize_mode_controller->OnAccelerometerUpdated(update);
   EXPECT_TRUE(maximize_mode_controller->IsMaximizeModeWindowManagerEnabled());
   bool maximize_mode_rotation_lock =
       maximize_mode_controller->rotation_locked();
@@ -826,16 +839,21 @@ TEST_F(DisplayPreferencesTest, LoadRotationIgnoredInNormalMode) {
   ash::MaximizeModeController* maximize_mode_controller =
       ash::Shell::GetInstance()->maximize_mode_controller();
   // Lid open to 90 degrees
-  maximize_mode_controller->
-      OnAccelerometerUpdated(gfx::Vector3dF(0.0f, 0.0f, 1.0f),
-                             gfx::Vector3dF(-1.0f, 0.0f, 0.0f));
+  ui::AccelerometerUpdate update;
+  update.Set(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD,
+             -kMeanGravity, 0.0f, 0.0f);
+  update.Set(ui::ACCELEROMETER_SOURCE_SCREEN,
+             -kMeanGravity, 0.0f, 0.0f);
+  maximize_mode_controller->OnAccelerometerUpdated(update);
   EXPECT_FALSE(maximize_mode_controller->IsMaximizeModeWindowManagerEnabled());
   EXPECT_FALSE(maximize_mode_controller->rotation_locked());
 
   // Open up 270 degrees to trigger maximize mode
-  maximize_mode_controller->
-      OnAccelerometerUpdated(gfx::Vector3dF(0.0f, 0.0f, -1.0f),
-                             gfx::Vector3dF(-1.0f, 0.0f, 0.0f));
+  update.Set(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD,
+             0.0f, 0.0f, kMeanGravity);
+  update.Set(ui::ACCELEROMETER_SOURCE_SCREEN,
+             0.0f, -kMeanGravity, 0.0f);
+  maximize_mode_controller->OnAccelerometerUpdated(update);
   EXPECT_TRUE(maximize_mode_controller->IsMaximizeModeWindowManagerEnabled());
   EXPECT_FALSE(maximize_mode_controller->rotation_locked());
 }

chrome/chrome_tests_unit.gypi

@@ -500,6 +500,7 @@
         '../third_party/icu/icu.gyp:icui18n',
         '../third_party/icu/icu.gyp:icuuc',
         '../third_party/libxml/libxml.gyp:libxml',
+        '../ui/accelerometer/ui_accelerometer.gyp:ui_accelerometer',
         '../ui/base/ui_base.gyp:ui_base_test_support',
         '../ui/gfx/gfx.gyp:gfx_test_support',
         '../ui/resources/ui_resources.gyp:ui_resources',

chromeos/DEPS

@@ -5,6 +5,6 @@ include_rules = [
   "+third_party/cros_system_api",
   "+third_party/libxml",
   "+third_party/protobuf",
-  "+ui/gfx/geometry",
+  "+ui/accelerometer",
   "+ui/gfx/x"
 ]

chromeos/accelerometer/accelerometer_reader.cc

@@ -52,6 +52,9 @@ const size_t kMaxAsciiUintLength = 21;
 // The time to wait between reading the accelerometer.
 const int kDelayBetweenReadsMs = 100;
 
+// The mean acceleration due to gravity on Earth in m/s^2.
+const float kMeanGravity = 9.80665f;
+
 // Reads |path| to the unsigned int pointed to by |value|. Returns true on
 // success or false on failure.
 bool ReadFileToUint(const base::FilePath& path, unsigned int* value) {
@@ -193,18 +196,18 @@ void AccelerometerReader::OnDataRead(
   DCHECK(!task_runner_->RunsTasksOnCurrentThread());
 
   if (success) {
-    gfx::Vector3dF base_reading, lid_reading;
     int16* values = reinterpret_cast<int16*>(reading->data);
-    base_reading.set_x(values[configuration_->data.index[0]]);
-    base_reading.set_y(values[configuration_->data.index[1]]);
-    base_reading.set_z(values[configuration_->data.index[2]]);
-    base_reading.Scale(1.0f / configuration_->data.base_scale);
-
-    lid_reading.set_x(values[configuration_->data.index[3]]);
-    lid_reading.set_y(values[configuration_->data.index[4]]);
-    lid_reading.set_z(values[configuration_->data.index[5]]);
-    lid_reading.Scale(1.0f / configuration_->data.lid_scale);
-    delegate_->HandleAccelerometerReading(base_reading, lid_reading);
+    float lid_scale = kMeanGravity / configuration_->data.lid_scale;
+    update_.Set(ui::ACCELEROMETER_SOURCE_SCREEN,
+                -values[configuration_->data.index[4]] * lid_scale,
+                values[configuration_->data.index[3]] * lid_scale,
+                values[configuration_->data.index[5]] * lid_scale);
+    float base_scale = kMeanGravity / configuration_->data.base_scale;
+    update_.Set(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD,
+                -values[configuration_->data.index[1]] * base_scale,
+                -values[configuration_->data.index[0]] * base_scale,
+                -values[configuration_->data.index[2]] * base_scale);
+    delegate_->HandleAccelerometerUpdate(update_);
   }
 
   // Trigger another read after the current sampling delay.

chromeos/accelerometer/accelerometer_reader.h

@@ -11,7 +11,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "chromeos/chromeos_export.h"
-#include "ui/gfx/geometry/vector3d_f.h"
+#include "ui/accelerometer/accelerometer_types.h"
 
 namespace base {
 class TaskRunner;
@@ -41,8 +41,8 @@ class CHROMEOS_EXPORT AccelerometerReader {
   // An interface to receive data from the AccelerometerReader.
   class Delegate {
    public:
-    virtual void HandleAccelerometerReading(const gfx::Vector3dF& base,
-                                            const gfx::Vector3dF& lid) = 0;
+    virtual void HandleAccelerometerUpdate(
+        const ui::AccelerometerUpdate& update) = 0;
   };
 
   AccelerometerReader(base::TaskRunner* blocking_task_runner,
@@ -58,8 +58,8 @@ class CHROMEOS_EXPORT AccelerometerReader {
   // OnDataRead with the result.
   void TriggerRead();
 
-  // If |success|, converts the raw reading to a pair of Vector3dF
-  // values and notifies the |delegate_| with the new readings.
+  // If |success|, converts the raw reading to an AccelerometerUpdate
+  // message and notifies the |delegate_| with the new readings.
   // Triggers another read from the accelerometer at the current sampling rate.
   void OnDataRead(scoped_refptr<Reading> reading, bool success);
 
@@ -69,6 +69,9 @@ class CHROMEOS_EXPORT AccelerometerReader {
   // A weak pointer to the delegate to send accelerometer readings to.
   Delegate* delegate_;
 
+  // The last seen accelerometer data.
+  ui::AccelerometerUpdate update_;
+
   // The accelerometer configuration.
   scoped_refptr<Configuration> configuration_;
 

chromeos/chromeos.gyp

@@ -28,7 +28,7 @@
         '../third_party/icu/icu.gyp:icui18n',
         '../third_party/libxml/libxml.gyp:libxml',
         '../third_party/protobuf/protobuf.gyp:protobuf_lite',
-        '../ui/gfx/gfx.gyp:gfx_geometry',
+        '../ui/accelerometer/ui_accelerometer.gyp:ui_accelerometer',
         '../url/url.gyp:url_lib',
         'cryptohome_proto',
         'ime/input_method.gyp:gencode',

ui/accelerometer/BUILD.gn

+# 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.
+
+import("//build/config/ui.gni")
+
+component("accelerometer") {
+  output_name = "ui_accelerometer"
+  sources = [
+    "accelerometer_types.cc",
+    "accelerometer_types.h",
+    "ui_accelerometer_export.h",
+  ]
+
+  defines = [ "UI_ACCELEROMETER_IMPLEMENTATION" ]
+
+  deps = [
+    "//ui/gfx/geometry",
+  ]
+}

ui/accelerometer/DEPS

+include_rules = [
+  "+ui/gfx/geometry/vector3d_f.h"
+]

ui/accelerometer/accelerometer_types.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 "ui/accelerometer/accelerometer_types.h"
+
+namespace ui {
+
+AccelerometerReading::AccelerometerReading() : present(false) {
+}
+
+AccelerometerReading::~AccelerometerReading() {
+}
+
+AccelerometerUpdate::AccelerometerUpdate() {
+}
+
+AccelerometerUpdate::~AccelerometerUpdate() {
+}
+
+}  // namespace ui

ui/accelerometer/accelerometer_types.h

+// 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.
+
+#ifndef UI_ACCEROMETER_ACCELEROMETER_TYPES_H_
+#define UI_ACCEROMETER_ACCELEROMETER_TYPES_H_
+
+#include "base/macros.h"
+#include "ui/accelerometer/ui_accelerometer_export.h"
+#include "ui/gfx/geometry/vector3d_f.h"
+
+namespace ui {
+
+enum AccelerometerSource {
+  // Accelerometer is located in the device's screen. In the screen's natural
+  // orientation, positive X points to the right, consistent with the pixel
+  // position. Positive Y points up the screen. Positive Z is perpendicular to
+  // the screen, pointing outwards towards the user. The orientation is
+  // described at:
+  // http://www.html5rocks.com/en/tutorials/device/orientation/.
+  ACCELEROMETER_SOURCE_SCREEN = 0,
+
+  // Accelerometer is located in a keyboard attached to the device's screen.
+  // If the device is open 180 degrees the orientation is consistent with the
+  // screen. I.e. Positive X points to the right, positive Y points up on the
+  // keyboard and positive Z is perpendicular to the keyboard pointing out
+  // towards the user.
+  ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD,
+
+  ACCELEROMETER_SOURCE_COUNT
+};
+
+struct UI_ACCELEROMETER_EXPORT AccelerometerReading {
+  AccelerometerReading();
+  ~AccelerometerReading();
+
+  // If true, this accelerometer is being updated.
+  bool present;
+
+  // The reading from this accelerometer measured in m/s^2.
+  gfx::Vector3dF reading;
+};
+
+// An accelerometer update contains the last known value for each of the
+// accelerometers present on the device.
+class UI_ACCELEROMETER_EXPORT AccelerometerUpdate {
+ public:
+  AccelerometerUpdate();
+  ~AccelerometerUpdate();
+
+  // Returns true if |source| has a valid value in this update.
+  bool has(AccelerometerSource source)  const {
+    return data_[source].present;
+  }
+
+  // Returns the last known value for |source|.
+  const gfx::Vector3dF& get(AccelerometerSource source) const {
+    return data_[source].reading;
+  }
+
+  void Set(AccelerometerSource source, float x, float y, float z) {
+    data_[source].present = true;
+    data_[source].reading.set_x(x);
+    data_[source].reading.set_y(y);
+    data_[source].reading.set_z(z);
+  }
+
+ protected:
+  AccelerometerReading data_[ACCELEROMETER_SOURCE_COUNT];
+
+  DISALLOW_COPY_AND_ASSIGN(AccelerometerUpdate);
+};
+
+}  // namespace chromeos
+
+#endif  // UI_ACCEROMETER_ACCELEROMETER_TYPES_H_

ui/accelerometer/ui_accelerometer.gyp

+# 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.
+
+{
+  'variables': {
+    'chromium_code': 1,
+  },
+  'targets': [
+    {
+      # GN version: //ui/accelerometer
+      'target_name': 'ui_accelerometer',
+      'type': '<(component)',
+      'dependencies': [
+        '../gfx/gfx.gyp:gfx_geometry',
+      ],
+      'defines': [
+        'UI_ACCELEROMETER_IMPLEMENTATION',
+      ],
+      'sources' : [
+        'accelerometer_types.cc',
+        'accelerometer_types.h',
+        'ui_accelerometer_export.h',
+      ],
+      'include_dirs': [
+        '../..',
+      ],
+    },
+  ],
+}

ui/accelerometer/ui_accelerometer_export.h

+// 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.
+
+#ifndef UI_ACCELEROMETER_UI_ACCELEROMETER_EXPORT_H_
+#define UI_ACCELEROMETER_UI_ACCELEROMETER_EXPORT_H_
+
+// Defines UI_ACCELEROMETER_EXPORT so that functionality implemented by the UI
+// accelerometer module can be exported to consumers.
+
+#if defined(COMPONENT_BUILD)
+
+#if defined(WIN32)
+
+#if defined(UI_ACCELEROMETER_IMPLEMENTATION)
+#define UI_ACCELEROMETER_EXPORT __declspec(dllexport)
+#else
+#define UI_ACCELEROMETER_EXPORT __declspec(dllimport)
+#endif
+
+#else  // !defined(WIN32)
+
+#if defined(UI_ACCELEROMETER_IMPLEMENTATION)
+#define UI_ACCELEROMETER_EXPORT __attribute__((visibility("default")))
+#else
+#define UI_ACCELEROMETER_EXPORT
+#endif
+
+#endif
+
+#else  // !defined(COMPONENT_BUILD)
+
+#define UI_ACCELEROMETER_EXPORT
+
+#endif
+
+#endif  // UI_ACCELEROMETER_UI_ACCELEROMETER_EXPORT_H_