add #url monkey patch to return https:// private urls

config/initializers/fog_google_https_private_urls.rb

+module Fog
+  module Storage
+    class GoogleXML
+      class File < Fog::Model
+        module MonkeyPatch
+          # Monkey patch this to use `get_https_url`
+          def url(expires)
+            requires :key
+            collection.get_https_url(key, expires)
+          end
+        end
+
+        prepend MonkeyPatch
+      end
+    end
+  end
+end

spec/initializers/fog_google_https_private_urls_spec.rb

+require 'spec_helper'
+
+describe Fog::Storage::GoogleXML::File do
+  let(:storage) do
+    Fog.mock!
+    Fog::Storage.new({
+                       google_storage_access_key_id: "asdf",
+                       google_storage_secret_access_key: "asdf",
+                       provider: "Google"
+                     })
+  end
+
+  let(:file) do
+    directory = storage.directories.create(key: 'data')
+    directory.files.create(
+      body: 'Hello World!',
+      key: 'hello_world.txt'
+    )
+  end
+
+  it 'delegates to #get_https_url' do
+    expect(file.url(Time.now)).to start_with("https://")
+  end
+end