Remove UrlDataSource::IsGzipped since it is not used

Added in https://codereview.chromium.org/2149323003, but
currently has no callers.

Change-Id: Ieb1de40e9a20f563b060e30db71516d68cdb6ec7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1903172Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713619}

content/public/browser/url_data_source.cc

@@ -127,10 +127,6 @@ std::string URLDataSource::GetAccessControlAllowOriginForOrigin(
   return std::string();
 }
 
-bool URLDataSource::IsGzipped(const std::string& path) {
-  return false;
-}
-
 void URLDataSource::DisablePolymer2ForHost(const std::string& host) {}
 
 bool URLDataSource::ShouldReplaceI18nInJS() {

content/public/browser/url_data_source.h

@@ -165,9 +165,6 @@ class CONTENT_EXPORT URLDataSource {
   virtual std::string GetAccessControlAllowOriginForOrigin(
       const std::string& origin);
 
-  // Whether |path| is gzipped (and should be transmitted gzipped).
-  virtual bool IsGzipped(const std::string& path);
-
   // Called on the UI thread. For the shared resource, disables using Polymer 2
   // for requests from |host|, even if WebUIPolymer2 is enabled. Assumes this
   // method is only called from one host.