Fix callback type in Chrome's ContentSetting#get() method.
Fix callback type in Chrome's ContentSetting#get() method.

The callback is marked as accepting no value, when in fact is supposed to
return the value requested by the caller. See [1] and https://crbug.com/1011585

[1] https://developer.chrome.com/extensions/contentSettings#type-ContentSetting

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Created by MOE: https://github.com/google/moe
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google/closure-compiler,Yannic/closure-compiler,vobruba-martin/closure-compiler,ChadKillingsworth/closure-compiler,ChadKillingsworth/closure-compiler,nawawi/closure-compiler,vobruba-martin/closure-compiler,nawawi/closure-compiler,monetate/closure-compiler,vobruba-martin/closure-compiler,Yannic/closure-compiler,nawawi/closure-compiler,ChadKillingsworth/closure-compiler,monetate/closure-compiler,nawawi/closure-compiler,Yannic/closure-compiler,google/closure-compiler,ChadKillingsworth/closure-compiler,monetate/closure-compiler,Yannic/closure-compiler,vobruba-martin/closure-compiler,monetate/closure-compiler,google/closure-compiler,google/closure-compiler