Defer ARC file system operations while ARC is booting.

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

Index: chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
diff --git a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
index 8bdf8d8d597bb3bc567b7ce0df9c59a6836f3355..d4887d65dac1698fa0793182644c4cd52818f0e7 100644
--- a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
+++ b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
@@ -14,8 +14,9 @@
 #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"
@@ -116,7 +117,20 @@ void ArcDocumentsProviderRoot::GetFileInfoWithDocumentId(
     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));
@@ -235,7 +249,7 @@ void ArcDocumentsProviderRoot::
 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,