Fix BlobBytesConsumer state assumption on cancellation

third_party/WebKit/Source/modules/fetch/BlobBytesConsumer.cpp

Index: third_party/WebKit/Source/modules/fetch/BlobBytesConsumer.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/BlobBytesConsumer.cpp b/third_party/WebKit/Source/modules/fetch/BlobBytesConsumer.cpp
index 19087874f63b0ed3d0c6747cf43a6451fddfe2af..ee586c0253242c7113c9b2fe9329df08afa18f6c 100644
--- a/third_party/WebKit/Source/modules/fetch/BlobBytesConsumer.cpp
+++ b/third_party/WebKit/Source/modules/fetch/BlobBytesConsumer.cpp
@@ -231,8 +231,14 @@ void BlobBytesConsumer::didFinishLoading(unsigned long identifier,
 
 void BlobBytesConsumer::didFail(const ResourceError& e) {
   if (e.isCancellation()) {
-    DCHECK_EQ(PublicState::Closed, m_state);
-    return;
+    // |m_loader| can be canceled when
+    //  - this object explicitly cancels it, or
+    //  - the global context is shutting down.
+    // In the first case, |m_state| should be Closed.
+    if (getExecutionContext() && !getExecutionContext()->isContextDestroyed())
+      DCHECK_EQ(PublicState::Closed, m_state);
+    if (m_state == PublicState::Closed)
+      return;
   }
   DCHECK_EQ(PublicState::ReadableOrWaiting, m_state);
   m_loader = nullptr;