Add an IPC to abort Stream construction.

content/browser/fileapi/fileapi_message_filter.cc

Index: content/browser/fileapi/fileapi_message_filter.cc
diff --git a/content/browser/fileapi/fileapi_message_filter.cc b/content/browser/fileapi/fileapi_message_filter.cc
index 66db0d781467ea7c72839c4d3b688f6f550d3499..b4b5aefc866fdaa0d599b4f093b8f8cf462f43fe 100644
--- a/content/browser/fileapi/fileapi_message_filter.cc
+++ b/content/browser/fileapi/fileapi_message_filter.cc
@@ -195,6 +195,7 @@ bool FileAPIMessageFilter::OnMessageReceived(
     IPC_MESSAGE_HANDLER(StreamHostMsg_SyncAppendSharedMemory,
                         OnAppendSharedMemoryToStream)
     IPC_MESSAGE_HANDLER(StreamHostMsg_FinishBuilding, OnFinishBuildingStream)
+    IPC_MESSAGE_HANDLER(StreamHostMsg_AbortBuilding, OnAbortBuildingStream)
     IPC_MESSAGE_HANDLER(StreamHostMsg_Clone, OnCloneStream)
     IPC_MESSAGE_HANDLER(StreamHostMsg_Remove, OnRemoveStream)
     IPC_MESSAGE_UNHANDLED(handled = false)
@@ -676,6 +677,13 @@ void FileAPIMessageFilter::OnFinishBuildingStream(const GURL& url) {
     stream->Finalize();
 }
 
+void FileAPIMessageFilter::OnAbortBuildingStream(const GURL& url) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  scoped_refptr<Stream> stream(GetStreamForURL(url));
+  if (stream.get())
+    stream->Abort();
+}
+
 void FileAPIMessageFilter::OnCloneStream(
     const GURL& url, const GURL& src_url) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));