XMLHttpRequest: return null upon failing responseArrayBuffer allocation.

third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp

Index: third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
diff --git a/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp b/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
index eae72e1e03323bca9e761c5068e30b3531e7451d..9ad95f53681a388ce38c6a8c8e4a161a2cb9c32a 100644
--- a/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
+++ b/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
@@ -387,11 +387,16 @@ DOMArrayBuffer* XMLHttpRequest::responseArrayBuffer() {
 
   if (!m_responseArrayBuffer) {
     if (m_binaryResponseBuilder && m_binaryResponseBuilder->size()) {
-      DOMArrayBuffer* buffer = DOMArrayBuffer::createUninitialized(
+      DOMArrayBuffer* buffer = DOMArrayBuffer::createUninitializedOrNull(
           m_binaryResponseBuilder->size(), 1);
-      m_binaryResponseBuilder->getAsBytes(
-          buffer->data(), static_cast<size_t>(buffer->byteLength()));
-      m_responseArrayBuffer = buffer;
+      if (buffer) {
+        m_binaryResponseBuilder->getAsBytes(
+            buffer->data(), static_cast<size_t>(buffer->byteLength()));
+        m_responseArrayBuffer = buffer;
+      }
+      // https://xhr.spec.whatwg.org/#arraybuffer-response allows clearing
+      // of the 'received bytes' payload when the response buffer allocation
+      // fails.

[haraken, 2017/03/03 19:23:26]

I guess it would be nicer to set an exception but the spec is not saying to do
so...

[sof, 2017/03/03 21:23:53]

https://github.com/whatwg/xhr/issues/26 has some discussion. That the getter
consistently returns null, makes for a more regular story.

       m_binaryResponseBuilder.clear();
     } else {
       m_responseArrayBuffer = DOMArrayBuffer::create(nullptr, 0);