Add more informative messages for DOM exceptions.

Source/modules/webaudio/AudioContext.cpp

Index: Source/modules/webaudio/AudioContext.cpp
diff --git a/Source/modules/webaudio/AudioContext.cpp b/Source/modules/webaudio/AudioContext.cpp
index e0c7792062c7f1edc01bed3342e2272e1f0e2b44..eefed5e05024316602a327524cb97a9aa7a011eb 100644
--- a/Source/modules/webaudio/AudioContext.cpp
+++ b/Source/modules/webaudio/AudioContext.cpp
@@ -28,6 +28,7 @@
 
 #include "modules/webaudio/AudioContext.h"
 
+#include "bindings/v8/ExceptionMessages.h"
 #include "bindings/v8/ExceptionState.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
@@ -293,7 +294,11 @@ PassRefPtr<AudioBuffer> AudioContext::createBuffer(unsigned numberOfChannels, si
 {
     RefPtr<AudioBuffer> audioBuffer = AudioBuffer::create(numberOfChannels, numberOfFrames, sampleRate);
     if (!audioBuffer.get()) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToConstruct(
+                "AudioBuffer",
+                "invalid number of channels, frames, or sample rate."));

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

For these kinds of errors, it would be nice to tell the developer which of the
numbers was invalid. That said, this is still strictly better than the previous
message. :)

[Raymond Toy (Google), 2013/09/27 16:24:10]

Agreed. I'll try to make this (and all others) more informative.  For this
particular one, it might be difficult to produce a more informative message
without access to the limits used in AudioBuffer::create.  (I'll need to check).

         return 0;
     }
 
@@ -304,13 +309,21 @@ PassRefPtr<AudioBuffer> AudioContext::createBuffer(ArrayBuffer* arrayBuffer, boo
 {
     ASSERT(arrayBuffer);
     if (!arrayBuffer) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToConstruct(
+                "AudioBuffer",
+                "invalid ArrayBuffer."));
         return 0;
     }
 
     RefPtr<AudioBuffer> audioBuffer = AudioBuffer::createFromAudioFileData(arrayBuffer->data(), arrayBuffer->byteLength(), mixToMono, sampleRate());
     if (!audioBuffer.get()) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToConstruct(
+                "AudioBuffer",
+                "invalid audio data in ArrayBuffer."));
         return 0;
     }
 
@@ -320,7 +333,12 @@ PassRefPtr<AudioBuffer> AudioContext::createBuffer(ArrayBuffer* arrayBuffer, boo
 void AudioContext::decodeAudioData(ArrayBuffer* audioData, PassRefPtr<AudioBufferCallback> successCallback, PassRefPtr<AudioBufferCallback> errorCallback, ExceptionState& es)
 {
     if (!audioData) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToExecute(
+                "decodeAudioData",
+                "AudioContext",
+                "invalid ArrayBuffer for audioData."));
         return;
     }
     m_audioDecoder.decodeAsync(audioData, sampleRate(), successCallback, errorCallback);
@@ -341,9 +359,12 @@ PassRefPtr<AudioBufferSourceNode> AudioContext::createBufferSource()
 
 PassRefPtr<MediaElementAudioSourceNode> AudioContext::createMediaElementSource(HTMLMediaElement* mediaElement, ExceptionState& es)
 {
-    ASSERT(mediaElement);

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

Why drop the ASSERT?

[Raymond Toy (Google), 2013/09/27 16:24:10]

When running the webaudio layout tests in debug mode, this ASSERT asserts and
crashes the test. Since we check mediaElement in the next line, we would not be
missing anything, while still allowing us to test this case in the layout test.

     if (!mediaElement) {
-        es.throwUninformativeAndGenericDOMException(InvalidStateError);
+        es.throwDOMException(
+            InvalidStateError,
+            ExceptionMessages::failedToConstruct(
+                "MediaElementAudioSourceNode",
+                "invalid HTMLMedialElement."));
         return 0;
     }
 
@@ -352,7 +373,11 @@ PassRefPtr<MediaElementAudioSourceNode> AudioContext::createMediaElementSource(H
 
     // First check if this media element already has a source node.
     if (mediaElement->audioSourceNode()) {
-        es.throwUninformativeAndGenericDOMException(InvalidStateError);
+        es.throwDOMException(
+            InvalidStateError,
+            ExceptionMessages::failedToConstruct(
+                "MediaElementAudioSourceNode",
+                "invalid HTMLMediaElement."));
         return 0;
     }
 
@@ -366,9 +391,10 @@ PassRefPtr<MediaElementAudioSourceNode> AudioContext::createMediaElementSource(H
 
 PassRefPtr<MediaStreamAudioSourceNode> AudioContext::createMediaStreamSource(MediaStream* mediaStream, ExceptionState& es)
 {
-    ASSERT(mediaStream);
     if (!mediaStream) {
-        es.throwUninformativeAndGenericDOMException(InvalidStateError);
+        es.throwDOMException(
+            InvalidStateError,
+            ExceptionMessages::failedToConstruct("MediaStreamAudioSourceNode"));

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

"invalid MediaStream source"?

         return 0;
     }
 
@@ -423,7 +449,11 @@ PassRefPtr<ScriptProcessorNode> AudioContext::createScriptProcessor(size_t buffe
     RefPtr<ScriptProcessorNode> node = ScriptProcessorNode::create(this, m_destinationNode->sampleRate(), bufferSize, numberOfInputChannels, numberOfOutputChannels);
 
     if (!node.get()) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToConstruct(
+                "ScriptProcessorNode",
+                "invalid buffer size, or number of input/outputs."));
         return 0;
     }
 
@@ -510,7 +540,11 @@ PassRefPtr<ChannelSplitterNode> AudioContext::createChannelSplitter(size_t numbe
     RefPtr<ChannelSplitterNode> node = ChannelSplitterNode::create(this, m_destinationNode->sampleRate(), numberOfOutputs);
 
     if (!node.get()) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToConstruct(
+                "ChannelSplitterNode",
+                "invalid number of outputs."));

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

"The number of outputs (" + String::number(numberOfOutputs) ") is invalid."?

It would be nice if you could give a pointer in the message as to what would be
valid: "We only support 17 outputs." or something. :)

         return 0;
     }
 
@@ -531,7 +565,11 @@ PassRefPtr<ChannelMergerNode> AudioContext::createChannelMerger(size_t numberOfI
     RefPtr<ChannelMergerNode> node = ChannelMergerNode::create(this, m_destinationNode->sampleRate(), numberOfInputs);
 
     if (!node.get()) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToConstruct(
+                "ChannelMergerNode",
+                "invalid number of inputs."));

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

Same as for outputs.

         return 0;
     }
 
@@ -557,7 +595,11 @@ PassRefPtr<PeriodicWave> AudioContext::createPeriodicWave(Float32Array* real, Fl
     ASSERT(isMainThread());
 
     if (!real || !imag || (real->length() != imag->length())) {
-        es.throwUninformativeAndGenericDOMException(SyntaxError);
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToConstruct(
+                "WaveTable",
+                "invalid real or imag arrays for wave table."));

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

One option would be to split this up into multiple exceptions: "Invalid real
array", "Invalid imaginary array", "The real array and imaginary array must be
the same length (8 vs 7)."

         return 0;
     }