[Mojo] Improve JavaScript API for MojoReadMessage

gin/converter.cc

Index: gin/converter.cc
diff --git a/gin/converter.cc b/gin/converter.cc
index 5fda6732fa8f2353a8ec1ea882c439e10c6c1f38..e60e3a0d288064ac76114f56f869a6f1e32966ee 100644
--- a/gin/converter.cc
+++ b/gin/converter.cc
@@ -6,6 +6,7 @@
 
 #include "v8/include/v8.h"
 
+using v8::ArrayBuffer;
 using v8::Boolean;
 using v8::External;
 using v8::Function;
@@ -125,6 +126,19 @@ bool Converter<Handle<Object> >::FromV8(Handle<Value> val,
   return true;
 }
 
+Handle<Value> Converter<Handle<ArrayBuffer> >::ToV8(v8::Isolate* isolate,
+                                                    Handle<ArrayBuffer> val) {
+  return val.As<Value>();
+}
+
+bool Converter<Handle<ArrayBuffer> >::FromV8(Handle<Value> val,
+                                             Handle<ArrayBuffer>* out) {
+  if (!val->IsArrayBuffer())
+    return false;
+  *out = Handle<ArrayBuffer>::Cast(val);
+  return true;
+}
+
 Handle<Value> Converter<Handle<External> >::ToV8(v8::Isolate* isolate,
                                                  Handle<External> val) {
   return val.As<Value>();