[Extensions Bindings] Add lastError utilities to APIBindingJSUtil

extensions/renderer/api_bindings_system_unittest.cc

 // Copyright 2016 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 "extensions/renderer/api_bindings_system.h"
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/stl_util.h"
@@ skipping 154 matching lines @@
     const std::string& expected_arguments) {
   ASSERT_TRUE(last_request());
   // Note that even if no arguments are provided by the API call, we should
   // have an empty list.
   ASSERT_TRUE(last_request()->arguments);
   EXPECT_EQ(expected_name, last_request()->method_name);
   EXPECT_EQ(ReplaceSingleQuotes(expected_arguments),
             ValueToString(*last_request()->arguments));
 }
 
-void APIBindingsSystemTest::CallFunctionOnObject(
+v8::Local<v8::Value> APIBindingsSystemTest::CallFunctionOnObject(
     v8::Local<v8::Context> context,
     v8::Local<v8::Object> object,
     const std::string& script_source) {
   std::string wrapped_script_source =
       base::StringPrintf("(function(obj) { %s })", script_source.c_str());
 
   v8::Local<v8::Function> func =
       FunctionFromString(context, wrapped_script_source);
-  ASSERT_FALSE(func.IsEmpty());
+  // Use ADD_FAILURE() to avoid messing up the return type with ASSERT.
+  if (func.IsEmpty()) {
+    ADD_FAILURE() << script_source;
+    return v8::Local<v8::Value>();
+  }
 
   v8::Local<v8::Value> argv[] = {object};
-  RunFunction(func, context, 1, argv);
+  return RunFunction(func, context, 1, argv);
 }
 
 // Tests API object initialization, calling a method on the supplied APIs, and
 // triggering the callback for the request.
 TEST_F(APIBindingsSystemTest, TestInitializationAndCallbacks) {
   v8::HandleScope handle_scope(isolate());
   v8::Local<v8::Context> context = MainContext();
 
   v8::Local<v8::Object> alpha_api = bindings_system()->CreateAPIInstance(
       kAlphaAPIName, context, isolate(), base::Bind(&AllowAllAPIs), nullptr);
@@ skipping 212 matching lines @@
   {
     // Test a simple call -> response.
     const char kTestCall[] = "obj.functionWithExternalRef({prop1: 'foo'});";
     CallFunctionOnObject(context, gamma_api, kTestCall);
     ValidateLastRequest("gamma.functionWithExternalRef", "[{'prop1':'foo'}]");
     reset_last_request();
   }
 }
 
 }  // namespace extensions