Added missing calls to ReadMessageEnd and writer.Flush.

Added unit tests for mime-type services extension.

src/ProtocolBuffers.Serialization/Http/MessageFormatFactory.cs

@@ -44,7 +44,9 @@ namespace Google.ProtocolBuffers.Serialization.Http
         {
             ICodedInputStream codedInput = CreateInputStream(options, contentType, input);
             codedInput.ReadMessageStart();
-            return (TBuilder)builder.WeakMergeFrom(codedInput, options.ExtensionRegistry);
+            builder.WeakMergeFrom(codedInput, options.ExtensionRegistry);
+            codedInput.ReadMessageEnd();
+            return builder;
         }
         
         /// <summary>
@@ -110,6 +112,7 @@ namespace Google.ProtocolBuffers.Serialization.Http
 
             // Write the closing message fragment
             codedOutput.WriteMessageEnd();
+            codedOutput.Flush();
         }
 
         private static ICodedInputStream ContentTypeToInputStream(string contentType, MessageFormatOptions options, Stream input)

src/ProtocolBuffers.Serialization/Http/ServiceExtensions.cs

@@ -27,6 +27,7 @@ namespace Google.ProtocolBuffers.Serialization.Http
             ICodedInputStream codedInput = MessageFormatFactory.CreateInputStream(options, contentType, input);
             codedInput.ReadMessageStart();
             IMessageLite response = stub.CallMethod(methodName, codedInput, options.ExtensionRegistry);
+            codedInput.ReadMessageEnd();
             response.WriteTo(options, responseType, output);
         }
     }

src/ProtocolBuffers.Test/ProtocolBuffers.Test.csproj

@@ -88,6 +88,7 @@
     </Compile>
     <Compile Include="Compatibility\TextCompatibilityTests.cs" />
     <Compile Include="Compatibility\XmlCompatibilityTests.cs" />
+    <Compile Include="TestRpcForMimeTypes.cs" />
     <Compile Include="TestReaderForUrlEncoded.cs" />
     <Compile Include="CSharpOptionsTest.cs" />
     <Compile Include="DeprecatedMemberTest.cs" />