Replace boolean return value SharedBuffer::getAsBytes with DCHECK

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

 /*
  *  Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
  *  Copyright (C) 2005-2007 Alexey Proskuryakov <ap@webkit.org>
  *  Copyright (C) 2007, 2008 Julien Chaffraix <jchaffraix@webkit.org>
  *  Copyright (C) 2008, 2011 Google Inc. All rights reserved.
  *  Copyright (C) 2012 Intel Corporation
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
@@ skipping 373 matching lines @@
 
   if (!m_responseArrayBuffer) {
     if (m_binaryResponseBuilder && m_binaryResponseBuilder->size()) {
       DOMArrayBuffer* buffer = DOMArrayBuffer::createUninitialized(
           m_binaryResponseBuilder->size(), 1);
       if (!m_binaryResponseBuilder->getAsBytes(
               buffer->data(), static_cast<size_t>(buffer->byteLength()))) {
         // m_binaryResponseBuilder failed to allocate an ArrayBuffer.
         // We need to crash the renderer since there's no way defined in
         // the spec to tell this to the user.
-        CRASH();
+        OOM_CRASH();

[tyoshino (SeeGerritForStatus), 2016/11/28 05:29:33]

This comment was correct when it was written. But now, the condition in the
if-clause is not returning success/fail of buffer allocation. Allocation happens
on L387.

https://chromium.googlesource.com/chromium/src/+/b2da98fba6daaf142757f3aa1b94...
When this comment was written, SharedBuffer::getAsArrayBuffer() contained a
buffer allocation call which is invocation of
ArrayBuffer::createUninitialized(). ArrayBuffer::createUninitialized() returned
nullptr on allocation failure.

https://chromium.googlesource.com/chromium/src/+/3dfbd2ef9d62505887e29f276625...
This change moved the DOMArrayBuffer creation out of getAsArrayBuffer(), but
https://chromium.googlesource.com/chromium/src/+/3dfbd2ef9d62505887e29f276625...
create() was returning nullptr when the given buffer is nullptr. So, it was
still correct.

https://chromium.googlesource.com/chromium/src/+/612660c50e4ae437e379b299fa75...
This change removed the nullptr check code from DOMArrayBuffer. The commit log
is suggesting that we should use createOrNull() when we want to get nullptr on
allocation failure, but it wasn't changed to do so.

https://chromium.googlesource.com/chromium/src/+/4a7f1339c93c0b19ec75779d93a0...
And, on the same day, this change refactored allocation and serialization into
two separate lines.

So, we should:
- call ArrayBuffer::createOrNull(). If it returns nullptr, call OOM_CRASH().
- call DOMArrayBuffer* create(PassRefPtr<WTF::ArrayBuffer> buffer) with the
created ArrayBuffer.
- when getAsBytes() fails, CRASH() as it's bad but not allocation failure.

       }
       m_responseArrayBuffer = buffer;
       m_binaryResponseBuilder.clear();
     } else {
       m_responseArrayBuffer = DOMArrayBuffer::create(nullptr, 0);
     }
   }
 
   return m_responseArrayBuffer.get();
 }
@@ skipping 1446 matching lines @@
   visitor->traceWrappers(m_responseDocument);
   visitor->traceWrappers(m_responseArrayBuffer);
   XMLHttpRequestEventTarget::traceWrappers(visitor);
 }
 
 std::ostream& operator<<(std::ostream& ostream, const XMLHttpRequest* xhr) {
   return ostream << "XMLHttpRequest " << static_cast<const void*>(xhr);
 }
 
 }  // namespace blink