[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..51ec0a696c9c9e288a798309c230da614315e194 100644
--- a/content/common/gin_java_bridge_messages.h
+++ b/content/common/gin_java_bridge_messages.h
@@ -45,14 +45,15 @@ 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 with the text from |error_message|.
 // 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 */,
+                           std::string /* error_message */)
 
 // Sent from renderer to browser in two cases:
 //