Switch browser/extensions/api/file_system/file_system_api.[h|cc] to the TaskScheduler API

chrome/browser/extensions/api/file_system/file_system_api.cc

Index: chrome/browser/extensions/api/file_system/file_system_api.cc
diff --git a/chrome/browser/extensions/api/file_system/file_system_api.cc b/chrome/browser/extensions/api/file_system/file_system_api.cc
index 966ec6635852503db2694689f1fab495b39c56f9..231215743a75f831d764e04565a1951c76b02bb7 100644
--- a/chrome/browser/extensions/api/file_system/file_system_api.cc
+++ b/chrome/browser/extensions/api/file_system/file_system_api.cc
@@ -506,6 +506,8 @@ ExtensionFunction::ResponseAction FileSystemGetDisplayPathFunction::Run() {
 FileSystemEntryFunction::FileSystemEntryFunction()
     : multiple_(false), is_directory_(false) {}
 
+FileSystemEntryFunction::~FileSystemEntryFunction() {}
+
 void FileSystemEntryFunction::PrepareFilesForWritableApp(
     const std::vector<base::FilePath>& paths) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
@@ -591,8 +593,8 @@ bool FileSystemGetWritableEntryFunction::RunAsync() {
           render_frame_host()->GetProcess()->GetID(), &path_, &error_))
     return false;
 
-  content::BrowserThread::PostTaskAndReply(
-      content::BrowserThread::FILE, FROM_HERE,
+  task_runner_->PostTaskAndReply(

[fdoray, 2017/05/16 15:23:26]

Unless RunAsync() is invoked multiple times on the same instance and it is
important to have mutual exclusion between calls to
SetIsDirectoryOnFileThread(), I don't think we need a sequence here.

You could simply write:

base::PostTaskWithTraitsAndReply(
  FROM_HERE,
  {base::MayBlock(), base::TaskPriority::BACKGROUND},
  base::BindOnce(&FileSystem...),
  base::BindOnce(&FileSystem...));

You can ask owners to confirm whether this is ok.

[Sébastien Marchand, 2017/05/16 15:53:09]

SGTM, I'll check with the owner to make sure that it's fine to run this in
parallel.

+      FROM_HERE,
       base::BindOnce(
           &FileSystemGetWritableEntryFunction::SetIsDirectoryOnFileThread,

[fdoray, 2017/05/16 15:23:26]

s/OnFileThread/Async/

[Sébastien Marchand, 2017/05/16 15:53:09]

Done.

           this),
@@ -616,7 +618,7 @@ void FileSystemGetWritableEntryFunction::CheckPermissionAndSendResponse() {
 }
 
 void FileSystemGetWritableEntryFunction::SetIsDirectoryOnFileThread() {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
+  DCHECK(task_runner_->RunsTasksInCurrentSequence());
   if (base::DirectoryExists(path_)) {
     is_directory_ = true;
   }
@@ -878,8 +880,8 @@ void FileSystemChooseEntryFunction::FilesSelected(
         file_manager::util::IsUnderNonNativeLocalPath(GetProfile(), paths[0]);
 #endif
 
-    content::BrowserThread::PostTask(
-        content::BrowserThread::FILE, FROM_HERE,
+    task_runner_->PostTask(

[fdoray, 2017/05/16 15:23:26]

ditto (a sequence may not be required)

[Sébastien Marchand, 2017/05/16 15:53:09]

Done.

+        FROM_HERE,
         base::BindOnce(
             &FileSystemChooseEntryFunction::ConfirmDirectoryAccessOnFileThread,
             this, non_native_path, paths, web_contents));
@@ -1114,8 +1116,8 @@ bool FileSystemChooseEntryFunction::RunAsync() {
     return true;
   }
 #endif
-  content::BrowserThread::PostTaskAndReplyWithResult(
-      content::BrowserThread::FILE, FROM_HERE,
+  base::PostTaskAndReplyWithResult(
+      task_runner_.get(), FROM_HERE,
       base::Bind(&base::DirectoryExists, previous_path),
       set_initial_path_callback);