The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3f89cb4d2e652514501cd26bcf7fd75f1fda73f8

commit 3f89cb4d2e652514501cd26bcf7fd75f1fda73f8
Author: nya <nya@chromium.org>
Date: Wed Mar 15 02:00:45 2017

mediaview: Hack to avoid Files app to freeze soon after login.

Files app freezes until storage::WatcherManager::AddWatcher() finishes.
To avoid this issue, add a hack to ArcDocumentsProviderRoot so that
AddWatcher() pretends to finish immediately.

Ideally this issue should be fixed in Files app. However its current
design assumes operations on changing the current working directory
are serialized. Therefore this change tries to workaround the issue in
a quick way.

BUG= chromium:698624 
TEST=Files app does not freeze soon after login.
TEST=unit_tests

Review-Url: https://codereview.chromium.org/2726373002
Cr-Commit-Position: refs/heads/master@{#456945}

[modify] https://crrev.com/3f89cb4d2e652514501cd26bcf7fd75f1fda73f8/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
[modify] https://crrev.com/3f89cb4d2e652514501cd26bcf7fd75f1fda73f8/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h
[modify] https://crrev.com/3f89cb4d2e652514501cd26bcf7fd75f1fda73f8/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root_unittest.cc

This is a follow-up of  Issue 684233 .

Your change meets the bar and is auto-approved for M58. Please go ahead and merge the CL to branch 3029 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), bhthompson@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7f1b243d17654d56433da28ad4d4e8865f7a3046

commit 7f1b243d17654d56433da28ad4d4e8865f7a3046
Author: Shuhei Takahashi <nya@chromium.org>
Date: Thu Mar 16 06:07:01 2017

mediaview: Hack to avoid Files app to freeze soon after login.

Files app freezes until storage::WatcherManager::AddWatcher() finishes.
To avoid this issue, add a hack to ArcDocumentsProviderRoot so that
AddWatcher() pretends to finish immediately.

Ideally this issue should be fixed in Files app. However its current
design assumes operations on changing the current working directory
are serialized. Therefore this change tries to workaround the issue in
a quick way.

BUG= chromium:698624 
TEST=Files app does not freeze soon after login.
TEST=unit_tests

Review-Url: https://codereview.chromium.org/2726373002
Cr-Commit-Position: refs/heads/master@{#456945}
(cherry picked from commit 3f89cb4d2e652514501cd26bcf7fd75f1fda73f8)

Review-Url: https://codereview.chromium.org/2753743005 .
Cr-Commit-Position: refs/branch-heads/3029@{#227}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}

[modify] https://crrev.com/7f1b243d17654d56433da28ad4d4e8865f7a3046/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
[modify] https://crrev.com/7f1b243d17654d56433da28ad4d4e8865f7a3046/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h
[modify] https://crrev.com/7f1b243d17654d56433da28ad4d4e8865f7a3046/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root_unittest.cc

59.0.3051.3/9404.0.0