Add a force-layout-height-to-zero layout mode to WebViewImpl

Source/core/frame/Settings.in

 # Defines properties which are available on the Settings object.
 #
 # Please think carefully before adding a new Setting.  Some questions to
 # consider are:
 # - Should this be a RuntimeEnabledFeature instead? Settings are for things
 #   which we support either values of at runtime.  Features are set at renderer
 #   process startup and are never changed. Features also tend to be set to a
 #   value based on the platform or the stability of the code in question, where
 #   as settings both codepaths need to be stable.
 # - How will you ensure test coverage of all relevant values of your setting?
@@ skipping 185 matching lines @@
 # One more Android SDK <= 18 quirk, removable 2015.
 # See http://crbug.com/306548
 viewportMetaMergeContentQuirk initial=false
 
 # This quirk is to maintain compatibility with Android apps.
 # It will be possible to remove it once WebSettings.{get|set}UseWideViewPort
 # API function will be removed.
 # See http://crbug.com/288037.
 wideViewportQuirkEnabled initial=false
 
+# Used by the android_webview to support a horizontal height auto-sizing
+# mode.
+forceZeroLayoutHeight initial=false, invalidate=ViewportDescription
+
 # Touch based text selection and editing on desktop.
 # crbug.com/304873 tracks removal once it's been enabled on all platforms.
 touchEditingEnabled initial=false
 
 # Settings for experimental desktop pinch-zoom support (with semantics
 # optimized for large screens).  Pinch-zoom generally is implemented mainly
 # outside of blink (in the compositor) and doesn't require any settings.
 # These settings are for an experimental modification to how pinch-zoom
 # behaves.  TODO(wjmaclean): link to design document.
 # crbug.com/304869 tracks removal.
@@ skipping 50 matching lines @@
 
 # This value indicates the maximum number of bytes a document is allowed
 # to transmit in Beacons (via navigator.sendBeacon()) -- Beacons are
 # intended to be smaller payloads transmitted as a page is unloading, not
 # a general (one-way) network transmission API.
 # The spec ( https://dvcs.w3.org/hg/webperf/raw-file/tip/specs/Beacon/Overview.html )
 # does not proscribe an upper limit, but allows for it -- the underlying
 # API will return 'false' in that case.
 maxBeaconTransmission type=int, initial=16384