net: Make UploadData::GetContentLength() asynchronous.

net/base/upload_data.h

Index: net/base/upload_data.h
diff --git a/net/base/upload_data.h b/net/base/upload_data.h
index 31c1958a6966c9e321f554754819b54f0c98726e..43d209b31dd141bd60697bfec3973761b19d84fb 100644
--- a/net/base/upload_data.h
+++ b/net/base/upload_data.h
@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
 #include "base/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
@@ -107,7 +108,6 @@ class NET_EXPORT UploadData : public base::RefCounted<UploadData> {
 
     // Returns the byte-length of the element.  For files that do not exist, 0
     // is returned.  This is done for consistency with Mozilla.
-    // Once called, this function will always return the same value.
     uint64 GetContentLength();
 
     // Returns a FileStream opened for reading for this element, positioned at
@@ -163,8 +163,26 @@ class NET_EXPORT UploadData : public base::RefCounted<UploadData> {
   void set_is_chunked(bool set) { is_chunked_ = set; }
   bool is_chunked() const { return is_chunked_; }
 
+  // Gets the total size in bytes of the data to upload. Computing the
+  // content length can result in performing file IO hence the operation is
+  // done asynchronously. Runs the callback with the content length once the
+  // computation is done.
+  typedef base::Callback<void(uint64 content_length)> ContentLengthCallback;
+  void GetContentLength(const ContentLengthCallback& callback);
+
+  // Returns the total size in bytes of the data to upload, for testing.
+  // This version may perform file IO on the current thread. This function
+  // will fail if called on a thread where file IO is prohibited. Usually
+  // used for testing, but Chrome Frame also uses this version.
+  uint64 GetContentLengthSync();
+
   // Returns the total size in bytes of the data to upload.
-  uint64 GetContentLength();
+  // This version may perform file IO on the current thread, but
+  // ThreadRestrictions::AllowIO is placed so this function won't crash even
+  // if it's called on a thread where file IO is prohibited.
+  //
+  // TODO(satorux): Remove this once clients are gone.
+  uint64 GetContentLengthSyncHack();
 
   // Returns true if the upload data is entirely in memory (i.e. the
   // upload data is not chunked, and all elemnts are of TYPE_BYTES).
@@ -187,6 +205,9 @@ class NET_EXPORT UploadData : public base::RefCounted<UploadData> {
   int64 identifier() const { return identifier_; }
 
  private:
+  // Helper function for GetContentLength().
+  void DoGetContentLength(uint64* content_length);
+
   friend class base::RefCounted<UploadData>;
 
   ~UploadData();