Invalidate the text autosizer on meta viewport settings changes

third_party/WebKit/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?
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 backgroundHtmlParserPendingTokenLimit type=unsigned, initial=0
 
 # Html preload scanning is a fast, early scan of HTML documents to find loadable
 # resources before the parser advances to them. If it is disabled, resources will
 # be loaded later.
 doHtmlPreloadScanning initial=true
 
 pluginsEnabled initial=false
 
 viewportEnabled initial=false, invalidate=ViewportDescription
-viewportMetaEnabled initial=false
+viewportMetaEnabled initial=false, invalidate=ViewportDescription
 
 dnsPrefetchingEnabled initial=false, invalidate=DNSPrefetching
 
 dataSaverEnabled initial=false
 
 # FIXME: This is a temporary flag and should be removed
 # when squashing is ready. (crbug.com/261605)
 layerSquashingEnabled initial=false
 
 # Clients that execute script should call ScriptController::canExecuteScripts()
@@ skipping 135 matching lines @@
 # Variant of the ParseHTMLOnMainThread experiment. This is designed to coalesce
 # TokenizedChunks when the experiment is running in threaded mode.
 parseHTMLOnMainThreadCoalesceChunks initial=false
 
 # Whether the CSSPreloadScanner is used for externally CSS preloads. NoPreload
 # indicates that the scanner will be used, but no preloads issued.
 cssExternalScannerNoPreload initial=false
 cssExternalScannerPreload initial=false
 
 browserSideNavigationEnabled initial=false