Have media gallery (through native media file util) use MIME sniffer

webkit/fileapi/media/device_media_async_file_util.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/fileapi/media/device_media_async_file_util.h"
 
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/single_thread_task_runner.h"
 #include "webkit/fileapi/file_system_context.h"
 #include "webkit/fileapi/file_system_operation_context.h"
 #include "webkit/fileapi/file_system_task_runners.h"
 #include "webkit/fileapi/file_system_url.h"
 #include "webkit/fileapi/isolated_context.h"
 #include "webkit/fileapi/media/filtering_file_enumerator.h"
 #include "webkit/fileapi/media/media_path_filter.h"
 #include "webkit/fileapi/media/mtp_device_async_delegate.h"
 #include "webkit/fileapi/media/mtp_device_file_system_config.h"
 #include "webkit/fileapi/media/mtp_device_map_service.h"
+#include "webkit/fileapi/media/native_media_file_util.h"
 
 namespace fileapi {
 
 namespace {
 
 const base::FilePath::CharType kDeviceMediaAsyncFileUtilTempDir[] =
     FILE_PATH_LITERAL("DeviceMediaFileSystem");
 
 // Returns true if the current thread is IO thread.
 bool IsOnIOThread(FileSystemOperationContext* context) {
@@ skipping 275 matching lines @@
     const AsyncFileUtil::ReadDirectoryCallback& callback,
     base::PlatformFileError error) {
   if (!callback.is_null())
     callback.Run(error, AsyncFileUtil::EntryList(), false /*no more*/);
 }
 
 void DeviceMediaAsyncFileUtil::OnDidCreateSnapshotFile(
     const AsyncFileUtil::CreateSnapshotFileCallback& callback,
     const base::PlatformFileInfo& file_info,
     const base::FilePath& platform_path) {
-  if (!callback.is_null())
-    callback.Run(base::PLATFORM_FILE_OK, file_info, platform_path,
-                 kSnapshotFileTemporary);
+  if (!callback.is_null()) {

[vandebo (ex-Chrome), 2013/03/25 19:02:11]

After looking at this a bit more, I'm not sure it's correct. 
OnSnapshotFileCreatedRunTask is what points to this function and it is passed as
a success callback.  There's something else passed as a failure callback.  So I
think the way the code is structured currently assumes that once we're to this
step there's no way to fail anymore.  With this change that's not the case
anymore.

It would be ok to roll this part back and approach it in a different CL.

[Kevin Bailey, 2013/04/03 18:05:07]

Chatted with vandebo and it looks ok to us, but I will step through it and
figure out who ultimately cares if the create snapshot succeeds or not. There is
a concern that the entity responsible for cleaning up the snapshot file may
think it was never created.

+    base::PlatformFileError error =
+        NativeMediaFileUtil::IsMediaFile(platform_path);
+    callback.Run(error, file_info, platform_path, kSnapshotFileTemporary);
+  }
 }
 
 void DeviceMediaAsyncFileUtil::OnCreateSnapshotFileError(
     const AsyncFileUtil::CreateSnapshotFileCallback& callback,
     base::PlatformFileError error) {
   if (!callback.is_null())
     callback.Run(error, base::PlatformFileInfo(), base::FilePath(),
                  kSnapshotFileTemporary);
 }
 
@@ skipping 17 matching lines @@
       *snapshot_file_path,
       base::Bind(&DeviceMediaAsyncFileUtil::OnDidCreateSnapshotFile,
                  weak_ptr_factory_.GetWeakPtr(),
                  callback),
       base::Bind(&DeviceMediaAsyncFileUtil::OnCreateSnapshotFileError,
                  weak_ptr_factory_.GetWeakPtr(),
                  callback));
 }
 
 }  // namespace fileapi