Defer ARC file system operations while ARC is booting.

chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc

 // Copyright 2016 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 "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
+#include "base/time/time.h"
 #include "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h"
-#include "chrome/browser/chromeos/arc/fileapi/arc_file_system_instance_util.h"
+#include "chrome/browser/chromeos/arc/fileapi/arc_file_system_operation_runner_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/base/mime_util.h"
 #include "url/gurl.h"
 
 using content::BrowserThread;
 using EntryList = storage::AsyncFileUtil::EntryList;
 
 namespace arc {
 
 namespace {
@@ skipping 80 matching lines @@
                  weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void ArcDocumentsProviderRoot::GetFileInfoWithDocumentId(
     const GetFileInfoCallback& callback,
     const std::string& document_id) {
   if (document_id.empty()) {
     callback.Run(base::File::FILE_ERROR_NOT_FOUND, base::File::Info());
     return;
   }
-  file_system_instance_util::GetDocumentOnIOThread(
+  // Specially handle the root directory since Files app does not update the
+  // list of file systems (left pane) until all volumes respond to GetMetadata
+  // requests to root directories.
+  if (document_id == root_document_id_) {
+    base::File::Info info;
+    info.size = -1;
+    info.is_directory = true;
+    info.is_symbolic_link = false;
+    info.last_modified = info.last_accessed = info.creation_time =
+        base::Time::UnixEpoch();

[hashimoto, 2017/01/23 08:28:42]

Please add a brief comment to describe why you chose base::Time::UnixEpoch(),
instead of any other values (e.g. base::Time()).

[Shuhei Takahashi, 2017/01/23 09:17:51]

Any value should work, so I have nothing to comment. Or if you have any
suggestion to use any specific value here, please let me know.

[hashimoto, 2017/01/24 04:05:45]

Then it'd be nice to have a comment which says this value was arbitrarily chosen
and any other value should also work well.
That kind of comment would help future developers who may be going to replace
this code with new code.

[Shuhei Takahashi, 2017/01/24 04:18:04]

Done.

+    callback.Run(base::File::FILE_OK, info);
+    return;
+  }
+  file_system_operation_runner_util::GetDocumentOnIOThread(
       authority_, document_id,
       base::Bind(&ArcDocumentsProviderRoot::GetFileInfoWithDocument,
                  weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void ArcDocumentsProviderRoot::GetFileInfoWithDocument(
     const GetFileInfoCallback& callback,
     mojom::DocumentPtr document) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (document.is_null()) {
@@ skipping 98 matching lines @@
   }
   ResolveToDocumentIdRecursively(iter->second.document_id,
                                  std::vector<base::FilePath::StringType>(
                                      components.begin() + 1, components.end()),
                                  callback);
 }
 
 void ArcDocumentsProviderRoot::ReadDirectoryInternal(
     const std::string& document_id,
     const ReadDirectoryInternalCallback& callback) {
-  file_system_instance_util::GetChildDocumentsOnIOThread(
+  file_system_operation_runner_util::GetChildDocumentsOnIOThread(
       authority_, document_id,
       base::Bind(
           &ArcDocumentsProviderRoot::ReadDirectoryInternalWithChildDocuments,
           weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void ArcDocumentsProviderRoot::ReadDirectoryInternalWithChildDocuments(
     const ReadDirectoryInternalCallback& callback,
     base::Optional<std::vector<mojom::DocumentPtr>> maybe_children) {
   if (!maybe_children) {
@@ skipping 33 matching lines @@
 
     mapping[filename] =
         ThinDocument{document->document_id,
                      document->mime_type == kAndroidDirectoryMimeType};
   }
 
   callback.Run(base::File::FILE_OK, std::move(mapping));
 }
 
 }  // namespace arc