Add more informative messages for DOM exceptions.

Source/modules/webaudio/AudioBuffer.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 14 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 
 #if ENABLE(WEB_AUDIO)
 
 #include "modules/webaudio/AudioBuffer.h"
 
+#include "bindings/v8/ExceptionMessages.h"
 #include "bindings/v8/ExceptionState.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/platform/audio/AudioBus.h"
 #include "core/platform/audio/AudioFileReader.h"
 #include "modules/webaudio/AudioContext.h"
 
 namespace WebCore {
 
 PassRefPtr<AudioBuffer> AudioBuffer::create(unsigned numberOfChannels, size_t numberOfFrames, float sampleRate)
 {
@@ skipping 45 matching lines @@
 }
 
 void AudioBuffer::releaseMemory()
 {
     m_channels.clear();
 }
 
 PassRefPtr<Float32Array> AudioBuffer::getChannelData(unsigned channelIndex, ExceptionState& es)
 {
     if (channelIndex >= m_channels.size()) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToGet(
+                "getChannelData",

[Mike West, 2013/09/27 06:44:39]

If this is called as `ab.getChannelData()`, then I'd prefer
'ExceptionMessages::failedToExecute'. 'failedToGet' implies direct property
access, which I don't think this maps to.

+                "AudioBuffer",
+                "invalid channel index."));

[Mike West, 2013/09/27 06:44:39]

How about "The provided index (" + String::number(channelIndex) + ") is
invalid."?

         return 0;
     }
 
     Float32Array* channelData = m_channels[channelIndex].get();
     return Float32Array::create(channelData->buffer(), channelData->byteOffset(), channelData->length());
 }
 
 Float32Array* AudioBuffer::getChannelData(unsigned channelIndex)
 {
     if (channelIndex >= m_channels.size())
         return 0;
 
     return m_channels[channelIndex].get();
 }
 
 void AudioBuffer::zero()
 {
     for (unsigned i = 0; i < m_channels.size(); ++i) {
         if (getChannelData(i))
             getChannelData(i)->zeroRange(0, length());
     }
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)