bindings: Use ExceptionMessages when an interface/callback conversion fails.

third_party/WebKit/Source/bindings/core/v8/NativeValueTraitsImplTest.cpp

 // Copyright 2017 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 "bindings/core/v8/NativeValueTraitsImpl.h"
 
 #include <utility>
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/IDLTypes.h"
 #include "bindings/core/v8/TestSequenceCallback.h"
@@ skipping 13 matching lines @@
 }
 
 TEST(NativeValueTraitsImplTest, IDLInterface) {
   V8TestingScope scope;
   {
     DummyExceptionStateForTesting exception_state;
     Internals* internals = NativeValueTraits<Internals>::NativeValue(
         scope.GetIsolate(), v8::Number::New(scope.GetIsolate(), 42),
         exception_state);
     EXPECT_TRUE(exception_state.HadException());
-    EXPECT_EQ("Unable to convert value to Internals.",
+    EXPECT_EQ("Failed to convert value to 'Internals'.",
               exception_state.Message());
     EXPECT_EQ(nullptr, internals);
   }
   {
     DummyExceptionStateForTesting exception_state;
     TestSequenceCallback* callback_function =
         NativeValueTraits<TestSequenceCallback>::NativeValue(
             scope.GetIsolate(), v8::Undefined(scope.GetIsolate()),
             exception_state);
     EXPECT_TRUE(exception_state.HadException());
-    EXPECT_EQ("Unable to convert value to TestSequenceCallback.",
+    EXPECT_EQ("Failed to convert value to 'TestSequenceCallback'.",
               exception_state.Message());
     EXPECT_EQ(nullptr, callback_function);
   }
 }
 
 void ThrowException(v8::Local<v8::Name>,
                     const v8::PropertyCallbackInfo<v8::Value>& info) {
   info.GetIsolate()->ThrowException(V8String(info.GetIsolate(), "bogus!"));
 }
 
@@ skipping 213 matching lines @@
     EXPECT_EQ(1U, record.size());
     EXPECT_EQ("foo", record[0].first);
     EXPECT_EQ("Hello, World!", record[0].second[0]);
     EXPECT_EQ("Hi, Mom!", record[0].second[1]);
   }
 }
 
 }  // namespace
 
 }  // namespace blink