In BlobURLRequestJob, open files asynchronously to avoid blocking the IO thread

webkit/blob/blob_url_request_job.h

Index: webkit/blob/blob_url_request_job.h
diff --git a/webkit/blob/blob_url_request_job.h b/webkit/blob/blob_url_request_job.h
index 2dec52274fd73c58faf2882079ce8f982c76df2e..68d532081322be65adc767ed9462278d481c75ae 100644
--- a/webkit/blob/blob_url_request_job.h
+++ b/webkit/blob/blob_url_request_job.h
@@ -11,7 +11,6 @@
 #include "base/scoped_ptr.h"
 #include "base/task.h"
 #include "net/base/completion_callback.h"
-#include "net/base/file_stream.h"
 #include "net/http/http_byte_range.h"
 #include "net/url_request/url_request_job.h"
 #include "webkit/blob/blob_data.h"
@@ -21,6 +20,10 @@ class MessageLoopProxy;
 struct PlatformFileInfo;
 }
 
+namespace net {
+class FileStream;
+}
+
 namespace webkit_blob {
 
 // A request job that handles reading blob URLs.
@@ -41,14 +44,17 @@ class BlobURLRequestJob : public net::URLRequestJob {
   virtual void SetExtraRequestHeaders(const net::HttpRequestHeaders& headers);
 
  private:
+  void CloseStream();
   void ResolveFile(const FilePath& file_path);
   void CountSize();
   void Seek(int64 offset);
   void AdvanceItem();
   void AdvanceBytesRead(int result);
+  int ComputeBytesToRead();
   bool ReadLoop(int* bytes_read);
   bool ReadItem();
   bool ReadBytes(const BlobData::Item& item, int bytes_to_read);
+  bool DispatchReadFile(const BlobData::Item& item, int bytes_to_read);
   bool ReadFile(const BlobData::Item& item, int bytes_to_read);
   void HeadersCompleted(int status_code, const std::string& status_txt);
   int ReadCompleted();
@@ -58,6 +64,9 @@ class BlobURLRequestJob : public net::URLRequestJob {
   void DidStart();
   void DidResolve(base::PlatformFileError rv,
                   const base::PlatformFileInfo& file_info);
+  void DidOpen(base::PlatformFileError rv,
+               base::PassPlatformFile file,
+               bool created);
   void DidRead(int result);
 
   base::ScopedCallbackFactory<BlobURLRequestJob> callback_factory_;
@@ -65,7 +74,7 @@ class BlobURLRequestJob : public net::URLRequestJob {
   scoped_refptr<base::MessageLoopProxy> file_thread_proxy_;
   net::CompletionCallbackImpl<BlobURLRequestJob> io_callback_;
   std::vector<int64> item_length_list_;
-  net::FileStream stream_;
+  scoped_ptr<net::FileStream> stream_;
   size_t item_index_;
   int64 total_size_;
   int64 current_item_offset_;