Browser Plugin: Add HTML5-like postMessage support

content/renderer/browser_plugin/browser_plugin_bindings.cc

Index: content/renderer/browser_plugin/browser_plugin_bindings.cc
diff --git a/content/renderer/browser_plugin/browser_plugin_bindings.cc b/content/renderer/browser_plugin/browser_plugin_bindings.cc
index d8c75ad5bece01eaafc258f690db6a230278023b..cc1bd61dc2911c53b1c80ceeefb9263dc5c72c48 100644
--- a/content/renderer/browser_plugin/browser_plugin_bindings.cc
+++ b/content/renderer/browser_plugin/browser_plugin_bindings.cc
@@ -38,8 +38,9 @@ namespace content {
 
 namespace {
 
-const char kAddEventListener[] = "addEventListener";
-const char kRemoveEventListener[] = "removeEventListener";
+const char kAddEventListener[] = "addCustomEventListener";
+const char kRemoveEventListener[] = "removeCustomEventListener";
+const char kPostMessageMethod[] = "postMessage";
 const char kSrcAttribute[] = "src";
 
 BrowserPluginBindings* GetBindings(NPObject* object) {
@@ -55,6 +56,10 @@ bool IdentifierIsRemoveEventListener(NPIdentifier identifier) {
   return WebBindings::getStringIdentifier(kRemoveEventListener) == identifier;
 }
 
+bool IdentifierIsPostMessage(NPIdentifier identifier) {
+  return WebBindings::getStringIdentifier(kPostMessageMethod) == identifier;
+}
+
 bool IdentifierIsSrcAttribute(NPIdentifier identifier) {
   return WebBindings::getStringIdentifier(kSrcAttribute) == identifier;
 }
@@ -90,6 +95,7 @@ bool StringToNPVariant(const std::string &in, NPVariant *variant) {
 
 //------------------------------------------------------------------------------
 // Implementations of NPClass functions.  These are here to:
+// - Implement postMessage behavior.
 // - Implement src attribute.
 //------------------------------------------------------------------------------
 NPObject* BrowserPluginBindingsAllocate(NPP npp, NPClass* the_class) {
@@ -106,6 +112,9 @@ bool BrowserPluginBindingsHasMethod(NPObject* np_obj, NPIdentifier name) {
   if (!np_obj)
     return false;
 
+  if (IdentifierIsPostMessage(name))
+    return true;
+
   if (IdentifierIsAddEventListener(name))
     return true;
 
@@ -125,6 +134,37 @@ bool BrowserPluginBindingsInvoke(NPObject* np_obj, NPIdentifier name,
   if (!bindings)
     return false;
 
+  if (IdentifierIsPostMessage(name) && (arg_count == 2)) {
+    v8::Handle<v8::Value> v8_val = WebBindings::toV8Value(&args[0]);
+    // If serialization fails, there may be a V8 exception pending.
+    // Don't touch the V8 state (eg, to raise our own 'error calling
+    // method on NPObject' exception).
+    if (v8_val.IsEmpty())
+      // This might happen if toV8Value fails an allocation.
+      // Does SafeAllocation::newInstance throw an exception in this case?
+      return true;

[nasko, 2012/09/19 21:19:59]

return false?

[Fady Samuel, 2012/09/20 15:24:28]

Done.

+    WebSerializedScriptValue serialized_v8_val =
+        WebSerializedScriptValue::serialize(v8_val);
+    WebString message_string = serialized_v8_val.toString();
+    // Serialization can sometimes fail (the user might try to fax the
+    // |window|, for example); ::serialize will result in a
+    // DATA_CLONE_ERR being raised, but we still need to abort
+    // the postMessage() operation. There's no clear way to test
+    // for failure in WebSerializedScriptValue, but an empty string
+    // should signal an invalid object. (The serializer at a nonzero
+    // version will always write a version tag.)
+    // v8::TryCatch, for some reason, was not catching DATA_CLONE_ERR;
+    // if this worked, it would be the right way to go.
+    // (This isn't the only way that serialization might fail! Other
+    // exceptions are possible.)
+    if (!message_string.length())
+      return true;

[nasko, 2012/09/19 21:19:59]

return false?

[Fady Samuel, 2012/09/20 15:24:28]

Done.

+    string16 message(message_string);
+    string16 target_origin = String16FromNPVariant(args[1]);
+    bindings->instance()->PostMessage(message, target_origin);
+    return true;
+  }
+
   if (IdentifierIsAddEventListener(name) && (arg_count == 2)) {
     std::string event_name = StringFromNPVariant(args[0]);
     if (event_name.empty())