Be more careful when calling methods on chromeHidden

chrome/renderer/extensions/chrome_v8_context.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/extensions/chrome_v8_context.h"
 
 #include "base/logging.h"
 #include "base/string_split.h"
 #include "base/values.h"
 #include "chrome/common/extensions/extension_set.h"
@@ skipping 26 matching lines @@
   else
     return NULL;
 }
 
 bool ChromeV8Context::CallChromeHiddenMethod(
     const std::string& function_name,
     int argc,
     v8::Handle<v8::Value>* argv,
     v8::Handle<v8::Value>* result) const {
   v8::Context::Scope context_scope(v8_context_);
+  v8::TryCatch try_catch;

[Matt Perry, 2011/12/01 18:57:29]

Meh, this seems like overkill given that:
- we now only cast to X after testing that value->IsX
- v8 will crash anyway if we don't catch here

 
   // Look up the function name, which may be a sub-property like
   // "Port.dispatchOnMessage" in the hidden global variable.
   v8::Local<v8::Value> value = v8::Local<v8::Value>::New(
       ChromeV8Extension::GetChromeHidden(v8_context_));
   std::vector<std::string> components;
   base::SplitStringDontTrim(function_name, '.', &components);
   for (size_t i = 0; i < components.size(); ++i) {
-    if (!value.IsEmpty()) {
+    if (!value.IsEmpty() && value->IsObject()) {

[Aaron Boodman, 2011/12/01 05:58:32]

FYI: This is the part that actually fixes the bug, the other stuff is just extra
defense.

       value = v8::Local<v8::Object>::Cast(value)->Get(
           v8::String::New(components[i].c_str()));
+      if (try_catch.HasCaught()) {
+        NOTREACHED() << *v8::String::AsciiValue(try_catch.Exception());
+        return false;
+      }
     }
   }
 
-  // TODO(aa): CHECK that this succeeds. Can't do this now because not all
-  // callers know if the method they are calling exists. Should be able to fix
-  // this when all the bindings are converted to the new framework.
   if (value.IsEmpty() || !value->IsFunction()) {
     VLOG(1) << "Could not execute chrome hidden method: " << function_name;
     return false;
   }
 
   v8::Handle<v8::Value> result_temp =
       v8::Local<v8::Function>::Cast(value)->Call(v8::Object::New(), argc, argv);
+  if (try_catch.HasCaught()) {
+    NOTREACHED() << *v8::String::AsciiValue(try_catch.Exception());
+    return false;
+  }
   if (result)
     *result = result_temp;
   return true;
 }
 
 void ChromeV8Context::DispatchOnLoadEvent(bool is_extension_process,
                                           bool is_incognito_process) const {
   v8::HandleScope handle_scope;
   v8::Handle<v8::Value> argv[3];
   argv[0] = v8::String::New(extension_id_.c_str());
   argv[1] = v8::Boolean::New(is_extension_process);
   argv[2] = v8::Boolean::New(is_incognito_process);
   CallChromeHiddenMethod("dispatchOnLoad", arraysize(argv), argv, NULL);
 }
 
 void ChromeV8Context::DispatchOnUnloadEvent() const {
   v8::HandleScope handle_scope;
   CallChromeHiddenMethod("dispatchOnUnload", 0, NULL, NULL);
 }