Is it OK to start removing old code? Native Apps is the only reason settings need mainBrowserState and currentBrowserState side by side.

Native App Launcher should be disabled in M60 so it should be ok to remove after that (flag should be removed post launch).

So we wait for M60 to ship, not just branch, is that right? Targeting M62 then.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2596c5101b8b875c48fb6eed2461ef0f7eff838b

commit 2596c5101b8b875c48fb6eed2461ef0f7eff838b
Author: pkl <pkl@chromium.org>
Date: Wed Jun 21 09:26:46 2017

Removed IsNativeAppLauncherEnabled() experiment

The experiment flag is removed as well as the first layer of code
that is now unreachable. Subsequent CLs will remove additional
code from the code base.

BUG= 721921 

Review-Url: https://codereview.chromium.org/2894883004
Cr-Commit-Position: refs/heads/master@{#481156}

[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/app/main_controller.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/experimental_flags.h
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/experimental_flags.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/resources/Settings.bundle/Experimental.plist
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/tabs/tab.h
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/tabs/tab.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/tabs/tab_unittest.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/browser_view_controller.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/settings/content_settings_collection_view_controller.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/settings/content_settings_collection_view_controller_unittest.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/settings/settings_collection_view_controller.h
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/settings/settings_collection_view_controller.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/settings/settings_egtest.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/settings/settings_navigation_controller.h
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/settings/settings_navigation_controller.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/ui/settings/settings_navigation_controller_unittest.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/chrome/browser/web/external_app_launcher.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/clean/chrome/browser/ui/settings/settings_coordinator.mm
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/web/public/web_state/ui/crw_web_delegate.h
[modify] https://crrev.com/2596c5101b8b875c48fb6eed2461ef0f7eff838b/ios/web/web_state/ui/crw_web_controller.mm

I think comment 4 should refer to "post-branch" instead of "post-launch". 

Once M60 beta appears stable, it should be safe to remove the code on trunk. I'm resetting the milestone to M-61.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8e7ebe52367879faf4952e74a06827c88f2895dd

commit 8e7ebe52367879faf4952e74a06827c88f2895dd
Author: pkl <pkl@chromium.org>
Date: Fri Jun 23 09:37:23 2017

Removed NativeAppsCollectionViewController and related code.

After the deprecation of Native App Launcher, this code is no longer
accessible.

BUG= 721921 

Review-Url: https://codereview.chromium.org/2899213002
Cr-Commit-Position: refs/heads/master@{#481836}

[modify] https://crrev.com/8e7ebe52367879faf4952e74a06827c88f2895dd/ios/chrome/app/main_controller.mm
[modify] https://crrev.com/8e7ebe52367879faf4952e74a06827c88f2895dd/ios/chrome/browser/ui/commands/ios_command_ids.h
[modify] https://crrev.com/8e7ebe52367879faf4952e74a06827c88f2895dd/ios/chrome/browser/ui/settings/BUILD.gn
[modify] https://crrev.com/8e7ebe52367879faf4952e74a06827c88f2895dd/ios/chrome/browser/ui/settings/cells/BUILD.gn
[delete] https://crrev.com/6fd1487d6f52df3e7598a716e4095b408a0d6431/ios/chrome/browser/ui/settings/cells/native_app_item.h
[delete] https://crrev.com/6fd1487d6f52df3e7598a716e4095b408a0d6431/ios/chrome/browser/ui/settings/cells/native_app_item.mm
[delete] https://crrev.com/6fd1487d6f52df3e7598a716e4095b408a0d6431/ios/chrome/browser/ui/settings/cells/native_app_item_unittest.mm
[modify] https://crrev.com/8e7ebe52367879faf4952e74a06827c88f2895dd/ios/chrome/browser/ui/settings/material_cell_catalog_view_controller.mm
[delete] https://crrev.com/6fd1487d6f52df3e7598a716e4095b408a0d6431/ios/chrome/browser/ui/settings/native_apps_collection_view_controller.h
[delete] https://crrev.com/6fd1487d6f52df3e7598a716e4095b408a0d6431/ios/chrome/browser/ui/settings/native_apps_collection_view_controller.mm
[delete] https://crrev.com/6fd1487d6f52df3e7598a716e4095b408a0d6431/ios/chrome/browser/ui/settings/native_apps_collection_view_controller_private.h
[delete] https://crrev.com/6fd1487d6f52df3e7598a716e4095b408a0d6431/ios/chrome/browser/ui/settings/native_apps_collection_view_controller_unittest.mm
[modify] https://crrev.com/8e7ebe52367879faf4952e74a06827c88f2895dd/ios/chrome/browser/ui/settings/settings_navigation_controller.h
[modify] https://crrev.com/8e7ebe52367879faf4952e74a06827c88f2895dd/ios/chrome/browser/ui/settings/settings_navigation_controller.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ace092d0da824017b3bb62b9178534eb512bed46

commit ace092d0da824017b3bb62b9178534eb512bed46
Author: Peter K. Lee <pkl@chromium.org>
Date: Fri Jun 23 11:52:11 2017

Removed code that clears Google App Launcher data.

Now that Google App Launcher has been deprecated, there's nothing left
to be cleared.

Bug:  721921 ,227636
Change-Id: I32cf9f3ea7b458f80ef91e24984db379d9abe4cb
Reviewed-on: https://chromium-review.googlesource.com/544848
Commit-Queue: Peter Lee <pkl@chromium.org>
Commit-Queue: Louis Romero <lpromero@chromium.org>
Reviewed-by: Louis Romero <lpromero@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481855}
[modify] https://crrev.com/ace092d0da824017b3bb62b9178534eb512bed46/ios/chrome/browser/browsing_data/BUILD.gn
[modify] https://crrev.com/ace092d0da824017b3bb62b9178534eb512bed46/ios/chrome/browser/browsing_data/browsing_data_removal_controller.mm
[modify] https://crrev.com/ace092d0da824017b3bb62b9178534eb512bed46/ios/chrome/browser/browsing_data/ios_chrome_browsing_data_remover.h
[modify] https://crrev.com/ace092d0da824017b3bb62b9178534eb512bed46/ios/chrome/browser/ui/settings/clear_browsing_data_collection_view_controller.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9afd36cf279820b61a052866793227c015eb97a2

commit 9afd36cf279820b61a052866793227c015eb97a2
Author: pkl <pkl@chromium.org>
Date: Fri Jun 23 11:52:58 2017

Removed NativeAppNavigationController and related code

These are no longer being used.

BUG= 721921 

Review-Url: https://codereview.chromium.org/2897213002
Cr-Commit-Position: refs/heads/master@{#481857}

[modify] https://crrev.com/9afd36cf279820b61a052866793227c015eb97a2/ios/chrome/app/BUILD.gn
[modify] https://crrev.com/9afd36cf279820b61a052866793227c015eb97a2/ios/chrome/browser/browsing_data/BUILD.gn
[modify] https://crrev.com/9afd36cf279820b61a052866793227c015eb97a2/ios/chrome/browser/native_app_launcher/BUILD.gn
[delete] https://crrev.com/ba97ce5223dbe2daa4f4daf13f002a44f57862af/ios/chrome/browser/native_app_launcher/native_app_navigation_controller.h
[delete] https://crrev.com/ba97ce5223dbe2daa4f4daf13f002a44f57862af/ios/chrome/browser/native_app_launcher/native_app_navigation_controller.mm
[delete] https://crrev.com/ba97ce5223dbe2daa4f4daf13f002a44f57862af/ios/chrome/browser/native_app_launcher/native_app_navigation_controller_unittest.mm
[delete] https://crrev.com/ba97ce5223dbe2daa4f4daf13f002a44f57862af/ios/chrome/browser/native_app_launcher/native_app_navigation_util.h
[delete] https://crrev.com/ba97ce5223dbe2daa4f4daf13f002a44f57862af/ios/chrome/browser/native_app_launcher/native_app_navigation_util.mm
[delete] https://crrev.com/ba97ce5223dbe2daa4f4daf13f002a44f57862af/ios/chrome/browser/native_app_launcher/native_app_navigation_util_unittest.mm
[modify] https://crrev.com/9afd36cf279820b61a052866793227c015eb97a2/ios/chrome/browser/tabs/BUILD.gn
[modify] https://crrev.com/9afd36cf279820b61a052866793227c015eb97a2/ios/chrome/browser/ui/BUILD.gn
[modify] https://crrev.com/9afd36cf279820b61a052866793227c015eb97a2/ios/chrome/browser/ui/downloads/BUILD.gn
[modify] https://crrev.com/9afd36cf279820b61a052866793227c015eb97a2/ios/chrome/browser/ui/settings/BUILD.gn
[modify] https://crrev.com/9afd36cf279820b61a052866793227c015eb97a2/ios/chrome/test/BUILD.gn

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/01bb93bd39593337a615183abfe50776fbfc1206

commit 01bb93bd39593337a615183abfe50776fbfc1206
Author: Peter K. Lee <pkl@chromium.org>
Date: Fri Jul 14 18:52:28 2017

Removed Native App Launcher infobars

Bug:  721921 
Change-Id: Idc58d5076791ea511d0efcd1df944496883de220
Reviewed-on: https://chromium-review.googlesource.com/567393
Reviewed-by: Louis Romero <lpromero@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Lee <pkl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486819}
[modify] https://crrev.com/01bb93bd39593337a615183abfe50776fbfc1206/components/infobars/core/infobar_delegate.h
[modify] https://crrev.com/01bb93bd39593337a615183abfe50776fbfc1206/ios/chrome/app/strings/ios_strings.grd
[modify] https://crrev.com/01bb93bd39593337a615183abfe50776fbfc1206/ios/chrome/browser/native_app_launcher/BUILD.gn
[delete] https://crrev.com/b1ca34a0edebb9b81f7db3c58b759029a64d7baf/ios/chrome/browser/native_app_launcher/native_app_infobar_controller.h
[delete] https://crrev.com/b1ca34a0edebb9b81f7db3c58b759029a64d7baf/ios/chrome/browser/native_app_launcher/native_app_infobar_controller.mm
[delete] https://crrev.com/b1ca34a0edebb9b81f7db3c58b759029a64d7baf/ios/chrome/browser/native_app_launcher/native_app_infobar_controller_unittest.mm
[delete] https://crrev.com/b1ca34a0edebb9b81f7db3c58b759029a64d7baf/ios/chrome/browser/native_app_launcher/native_app_infobar_delegate.h
[delete] https://crrev.com/b1ca34a0edebb9b81f7db3c58b759029a64d7baf/ios/chrome/browser/native_app_launcher/native_app_infobar_delegate.mm
[delete] https://crrev.com/b1ca34a0edebb9b81f7db3c58b759029a64d7baf/ios/chrome/browser/native_app_launcher/native_app_infobar_delegate_unittest.mm
[delete] https://crrev.com/b1ca34a0edebb9b81f7db3c58b759029a64d7baf/ios/chrome/browser/native_app_launcher/native_app_navigation_controller_protocol.h
[modify] https://crrev.com/01bb93bd39593337a615183abfe50776fbfc1206/ios/chrome/browser/ui/infobars/infobar_view.h
[modify] https://crrev.com/01bb93bd39593337a615183abfe50776fbfc1206/ios/chrome/browser/ui/infobars/infobar_view.mm
[modify] https://crrev.com/01bb93bd39593337a615183abfe50776fbfc1206/ios/chrome/test/BUILD.gn

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/chrome/ios_internal.git/+/f2ea6b6eb5661f53abbb02fc8ef4437ffecf31ed

commit f2ea6b6eb5661f53abbb02fc8ef4437ffecf31ed
Author: pkl <pkl@google.com>
Date: Thu Jul 20 22:07:37 2017

This is ongoing code cleanup and doesn't need an associated milestone.

Marking histograms as obsolete:
https://critique.corp.google.com/#review/217703278
https://critique.corp.google.com/#review/219691953

I don't think there's anything else left.