Mojo: Implement support for |Foo&| mojom syntax

mojo/public/cpp/bindings/tests/request_response_unittest.cc

Index: mojo/public/cpp/bindings/tests/request_response_unittest.cc
diff --git a/mojo/public/cpp/bindings/tests/request_response_unittest.cc b/mojo/public/cpp/bindings/tests/request_response_unittest.cc
index c6cf11b27d69136ee9b9ea2efff858027d9c5dbf..338d9684dfdf94c440e9ca3a51dffdc472d611e4 100644
--- a/mojo/public/cpp/bindings/tests/request_response_unittest.cc
+++ b/mojo/public/cpp/bindings/tests/request_response_unittest.cc
@@ -50,7 +50,7 @@ class ProviderImpl : public InterfaceImpl<sample::Provider> {
 
 class StringRecorder {
  public:
-  StringRecorder(std::string* buf) : buf_(buf) {
+  explicit StringRecorder(std::string* buf) : buf_(buf) {
   }
   void Run(const String& a) const {
     *buf_ = a;
@@ -64,7 +64,7 @@ class StringRecorder {
 
 class EnumRecorder {
  public:
-  EnumRecorder(sample::Enum* value) : value_(value) {
+  explicit EnumRecorder(sample::Enum* value) : value_(value) {
   }
   void Run(sample::Enum a) const {
     *value_ = a;