Flesh out URLLoader's download_to_file function....

Flesh out URLLoader's download_to_file function.
* tie the lifetime of the resulting temp file to the lifetime of the URLLoader
 (the plan is to later extend the lifetime of the temp file to support xhr.responseBlob)
* make it work in test_shell
* make it work for sync requests
* added OnDataDownloaded messages to report progress

A related BlobURL loading change.
* grab a reference to the blob early on to ensure it's still there when the 'job' is finally started.

TEST=manual and deletable_file_reference_unittest.cc
BUG=52486, 56752
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=60862

[michaeln, 2010-09-28 02:32:04]

Same patch as before (http://codereview.chromium.org/3165062/show) with the
changes described here...

> Per http://code.google.com/p/chromium/issues/detail?id=56752...
>
> I'll resubmit this change with the addition of an extra line of code to
> conditionally send the new IPC only when needed.
>
>  if (request_.download_to_file)  // <--- this is the extra line
>
>    dispatcher_->message_sender()->Send(
>        new ViewHostMsg_ResourceLoaderDeleted(request_id_));
>
> Since the semantics of the message are changing, I'll rename the message to
> something along the lines of...
>  ViewHostMsg_ReleaseDownloadedFile(request_id_);

[darin (slow to review), 2010-09-28 06:14:41]

LGTM

[Paweł Hajdan Jr., 2010-09-28 08:42:15]

Drive-by with a test comment. Please make a follow-up CL.

http://codereview.chromium.org/3396029/diff/26002/17022
File webkit/blob/deletable_file_reference_unittest.cc (right):

http://codereview.chromium.org/3396029/diff/26002/17022#newcode20
webkit/blob/deletable_file_reference_unittest.cc:20:
file_util::CreateTemporaryFile(&file);
Please use ScopedTempDir to make sure we don't leak the temporary file.

[michaeln, 2010-09-28 19:09:23]

http://codereview.chromium.org/3396029/diff/26002/17022
File webkit/blob/deletable_file_reference_unittest.cc (right):

http://codereview.chromium.org/3396029/diff/26002/17022#newcode20
webkit/blob/deletable_file_reference_unittest.cc:20:
file_util::CreateTemporaryFile(&file);
On 2010/09/28 08:42:15, Paweł Hajdan Jr. wrote:
> Please use ScopedTempDir to make sure we don't leak the temporary file.

Done.

[Paweł Hajdan Jr., 2010-09-29 08:43:16]

LGTM