[Android] Java Bridge with Gin: implement Java Bridge dispatcher

content/common/gin_java_bridge_messages.h

Index: content/common/gin_java_bridge_messages.h
diff --git a/content/common/gin_java_bridge_messages.h b/content/common/gin_java_bridge_messages.h
index f9525b1e5a5c4ba11301855f47456977a1053ad0..cbce41385438e33daf3e312d43d3b036d3a3fb9d 100644
--- a/content/common/gin_java_bridge_messages.h
+++ b/content/common/gin_java_bridge_messages.h
@@ -7,6 +7,7 @@
 // Multiply-included message file, hence no include guard.
 
 #include "base/basictypes.h"
+#include "content/common/android/gin_java_bridge_errors.h"
 #include "content/common/content_export.h"
 #include "ipc/ipc_message_macros.h"
 
@@ -16,6 +17,8 @@
 
 // Messages for handling Java objects injected into JavaScript -----------------
 
+IPC_ENUM_TRAITS(content::GinJavaBridgeError)
+
 // Sent from browser to renderer to add a Java object with the given name.
 // Object IDs are generated on the browser side.
 IPC_MESSAGE_ROUTED2(GinJavaBridgeMsg_AddNamedObject,
@@ -45,14 +48,16 @@ IPC_SYNC_MESSAGE_ROUTED2_1(GinJavaBridgeHostMsg_HasMethod,
 // a container to work around immutability of base::Value.
 // Empty result list indicates that an error has happened on the Java side
 // (either bridge-induced error or an unhandled Java exception) and an exception
-// must be thrown into JavaScript.
+// must be thrown into JavaScript. |error_code| indicates the cause of
+// the error.
 // Some special value types that are not supported by base::Value are encoded
 // as BinaryValues via GinJavaBridgeValue.
-IPC_SYNC_MESSAGE_ROUTED3_1(GinJavaBridgeHostMsg_InvokeMethod,
+IPC_SYNC_MESSAGE_ROUTED3_2(GinJavaBridgeHostMsg_InvokeMethod,
                            int32 /* object_id */,
                            std::string /* method_name */,
                            base::ListValue /* arguments */,
-                           base::ListValue /* result */)
+                           base::ListValue /* result */,
+                           content::GinJavaBridgeError /* error_code */)
 
 // Sent from renderer to browser in two cases:
 //