Add 'state' to authorization params.

More information on https://developers.facebook.com/docs/reference/dialogs/oauth/

lib/omniauth/strategies/facebook.rb

@@ -88,6 +88,7 @@ module OmniAuth
       def authorize_params
         super.tap do |params|
           params.merge!(:display => request.params['display']) if request.params['display']
+          params.merge!(:state => request.params['state']) if request.params['state']
           params[:scope] ||= DEFAULT_SCOPE
         end
       end

spec/omniauth/strategies/facebook_spec.rb

@@ -62,6 +62,12 @@ describe OmniAuth::Strategies::Facebook do
       subject.authorize_params.should be_a(Hash)
       subject.authorize_params[:display].should eq('touch')
     end
+
+    it 'includes state parameter from request when present' do
+      @request.stub(:params) { { 'state' => 'some_state' } }
+      subject.authorize_params.should be_a(Hash)
+      subject.authorize_params[:state].should eq('some_state')
+    end
   end
 
   describe '#token_params' do