WebKit & WebCore part of the device motion implementation using the platform layer.

Source/WebCore/WebCore.gypi

 {
     'variables': {
         'project_dir': ['.'],
         'webcore_include_dirs': [
           '.',
           '..',
           'Modules/battery',
           'Modules/filesystem',
           'Modules/gamepad',
           'Modules/geolocation',
@@ skipping 3721 matching lines @@
             'platform/chromium/ClipboardChromium.h',
             'platform/chromium/ClipboardChromiumPosix.cpp',
             'platform/chromium/ClipboardChromiumWin.cpp',
             'platform/chromium/ClipboardMimeTypes.cpp',
             'platform/chromium/ClipboardMimeTypes.h',
             'platform/chromium/ClipboardUtilitiesChromium.cpp',
             'platform/chromium/ClipboardUtilitiesChromium.h',
             'platform/chromium/ContextMenuChromium.cpp',
             'platform/chromium/ContextMenuItemChromium.cpp',
             'platform/chromium/CursorChromium.cpp',
+            'platform/chromium/DeviceMotionChromium.cpp',
             'platform/chromium/DragDataChromium.cpp',
             'platform/chromium/DragDataRef.h',
             'platform/chromium/DragImageChromiumSkia.cpp',
             'platform/chromium/DragImageRef.h',
             'platform/chromium/EventTracerChromium.cpp',
             'platform/chromium/FileSystemChromium.cpp',
             'platform/chromium/FileSystemChromiumLinux.cpp',
             'platform/chromium/FileSystemChromiumMac.mm',
             'platform/chromium/FileSystemChromiumWin.cpp',
             'platform/chromium/FramelessScrollView.cpp',
@@ skipping 44 matching lines @@
             'platform/chromium/SharedTimerChromium.cpp',
             'platform/chromium/SoundChromiumPosix.cpp',
             'platform/chromium/SoundChromiumWin.cpp',
             'platform/chromium/StatsCounterChromium.cpp',
             'platform/chromium/SuddenTerminationChromium.cpp',
             'platform/chromium/SystemTimeChromium.cpp',
             'platform/chromium/TemporaryLinkStubs.cpp',
             'platform/chromium/TraceEvent.h',
             'platform/chromium/VisitedLinksChromium.cpp',
             'platform/chromium/WidgetChromium.cpp',
+            'platform/chromium/support/WebDeviceMotionData.cpp',
+            'platform/chromium/support/WebDeviceMotionEventPump.h',
+            'platform/chromium/support/WebDeviceMotionEventPump.cpp',
             'platform/cocoa/KeyEventCocoa.h',
             'platform/cocoa/KeyEventCocoa.mm',
             'platform/graphics/ANGLEWebKitBridge.cpp',
             'platform/graphics/ANGLEWebKitBridge.h',
             'platform/graphics/BitmapImage.cpp',
             'platform/graphics/Color.cpp',
             'platform/graphics/CrossfadeGeneratedImage.cpp',
             'platform/graphics/CrossfadeGeneratedImage.h',
             'platform/graphics/Extensions3D.h',
             'platform/graphics/Font.cpp',
@@ skipping 2750 matching lines @@
           '<(SHARED_INTERMEDIATE_DIR)/WebCore/bindings/JSSVGZoomAndPan.cpp',
           '<(SHARED_INTERMEDIATE_DIR)/WebCore/bindings/JSSVGZoomAndPan.h',
           '<(SHARED_INTERMEDIATE_DIR)/WebCore/bindings/JSSVGZoomEvent.cpp',
           '<(SHARED_INTERMEDIATE_DIR)/WebCore/bindings/JSSVGZoomEvent.h',
         ],
         'export_file_generator_files': [
             '<(PRODUCT_DIR)/DerivedSources/WebCore/ExportFileGenerator.cpp',
         ],
     }
 }