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

webkit/fileapi/media/device_media_async_file_util.cc

Index: webkit/fileapi/media/device_media_async_file_util.cc
diff --git a/webkit/fileapi/media/device_media_async_file_util.cc b/webkit/fileapi/media/device_media_async_file_util.cc
index 2340a19fd5c164f1bb5c9773618b20a8772db609..66f2a5009a544af7ff4618535e2b74a7c7f44fff 100644
--- a/webkit/fileapi/media/device_media_async_file_util.cc
+++ b/webkit/fileapi/media/device_media_async_file_util.cc
@@ -17,6 +17,8 @@
 #include "webkit/fileapi/media/media_path_filter.h"
 #include "webkit/fileapi/media/mtp_device_async_delegate.h"
 #include "webkit/fileapi/media/mtp_device_map_service.h"
+#include "webkit/fileapi/media/native_media_file_util.h"
+#include "webkit/fileapi/native_file_util.h"
 
 namespace fileapi {
 
@@ -62,6 +64,15 @@ void CreateSnapshotFileOnBlockingPool(
   }
 }
 
+void CheckMediaFile(
+    const base::FilePath& file_path,
+    base::PlatformFileError* error) {
+  *error = NativeMediaFileUtil::IsMediaFile(file_path);
+  if (*error == base::PLATFORM_FILE_ERROR_SECURITY)
+    // It exists but we reject it. Try to clean up.
+    NativeFileUtil::DeleteFile(file_path);
+}
+
 }  // namespace
 
 DeviceMediaAsyncFileUtil::~DeviceMediaAsyncFileUtil() {
@@ -305,12 +316,30 @@ void DeviceMediaAsyncFileUtil::OnReadDirectoryError(
 }
 
 void DeviceMediaAsyncFileUtil::OnDidCreateSnapshotFile(
+    FileSystemOperationContext* context,
     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);
+  base::PlatformFileError* error = new base::PlatformFileError;
+  context->file_system_context()->task_runners()->media_task_runner()->
+      PostTaskAndReply(
+          FROM_HERE,
+          base::Bind(&CheckMediaFile, platform_path,
+                     base::Unretained(error)),
+          base::Bind(&DeviceMediaAsyncFileUtil::OnDidCheckMediaRunTask,
+                     weak_ptr_factory_.GetWeakPtr(),
+                     callback, file_info, platform_path,
+                     base::Owned(error)));
+}
+
+void DeviceMediaAsyncFileUtil::OnDidCheckMediaRunTask(
+    const AsyncFileUtil::CreateSnapshotFileCallback& callback,
+    const base::PlatformFileInfo& file_info,
+    const base::FilePath& platform_path,
+    base::PlatformFileError* error) {
+  if (!callback.is_null()) {
+    callback.Run(*error, file_info, platform_path, kSnapshotFileTemporary);
+  }
 }
 
 void DeviceMediaAsyncFileUtil::OnCreateSnapshotFileError(
@@ -341,6 +370,7 @@ void DeviceMediaAsyncFileUtil::OnSnapshotFileCreatedRunTask(
       *snapshot_file_path,
       base::Bind(&DeviceMediaAsyncFileUtil::OnDidCreateSnapshotFile,
                  weak_ptr_factory_.GetWeakPtr(),
+                 context,
                  callback),
       base::Bind(&DeviceMediaAsyncFileUtil::OnCreateSnapshotFileError,
                  weak_ptr_factory_.GetWeakPtr(),