Make WebFileSystemCallbacks not self-destruct, deprecate AsyncFileSystem

Source/core/core.gypi

 {
     'variables': {
         'deprecated_perl_core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSKeyframeRule.idl',
@@ skipping 2557 matching lines @@
             'html/track/TrackEvent.cpp',
             'html/track/WebVTTElement.cpp',
             'html/track/WebVTTElement.h',
             'html/track/WebVTTParser.cpp',
             'html/track/WebVTTParser.h',
             'html/track/WebVTTToken.h',
             'html/track/WebVTTTokenizer.cpp',
             'html/track/WebVTTTokenizer.h',
         ],
         'webcore_platform_files': [
-            'platform/AsyncFileSystem.h',
             'platform/AsyncFileSystemCallbacks.h',
             'platform/CalculationValue.cpp',
             'platform/CalculationValue.h',
             'platform/Clock.cpp',
             'platform/Clock.h',
             'platform/ContentType.cpp',
             'platform/ContentType.h',
             'platform/ContextMenu.cpp',
             'platform/ContextMenuItem.cpp',
             'platform/CrossThreadCopier.cpp',
@@ skipping 1162 matching lines @@
             'platform/chromium/support/WebActiveGestureAnimation.h',
             'platform/chromium/support/WebArrayBuffer.cpp',
             'platform/chromium/support/WebAudioBus.cpp',
             'platform/chromium/support/WebCrypto.cpp',
             'platform/chromium/support/WebCryptoAlgorithm.cpp',
             'platform/chromium/support/WebCryptoKey.cpp',
             'platform/chromium/support/WebCursorInfo.cpp',
             'platform/chromium/support/WebData.cpp',
             'platform/chromium/support/WebDeviceMotionData.cpp',
             'platform/chromium/support/WebDeviceOrientationData.cpp',
+            'platform/chromium/support/WebFileSystemCallbacks.cpp',
             'platform/chromium/support/WebFloatQuad.cpp',
             'platform/chromium/support/WebHTTPBody.cpp',
             'platform/chromium/support/WebHTTPLoadInfo.cpp',
             'platform/chromium/support/WebMediaConstraints.cpp',
             'platform/chromium/support/WebMediaStream.cpp',
             'platform/chromium/support/WebMediaStreamSource.cpp',
             'platform/chromium/support/WebMediaStreamTrack.cpp',
             'platform/chromium/support/WebPrerender.cpp',
             'platform/chromium/support/WebPrerenderingSupport.cpp',
             'platform/chromium/support/WebRTCConfiguration.cpp',
@@ skipping 103 matching lines @@
                 'bison_exe': 'bison',
                 # We specify a preprocess so it happens locally and won't get
                 # distributed to goma.
                 # FIXME: /usr/bin/gcc won't exist on OSX forever. We want to
                 # use /usr/bin/clang once we require Xcode 4.x.
                 'preprocessor': '--preprocessor "/usr/bin/gcc -E -P -x c++"'
               }],
          ],
     }
 }