Can you please run: 'gsettings get org.gnome.desktop.wm.preferences button-layout' and paste the output here.

Where are the buttons for other apps, e.g. the terminal window?

Also, this is (G)ubuntu 14.04, right?

$ gsettings get org.gnome.desktop.wm.preferences button-layout
'close,minimize,maximize:'

That's strange. The value matches what chrome is doing for its custom bar, but no other windows actually use this layout.

The buttons for all other windows are on the upper right (matching "system bar.png" in the description).

Yes, I'm on 14.04.

So I tried to grep through the gsettings values and these seem relevant:
org.cinnamon.muffin button-layout ':minimize,maximize,close'
org.gnome.desktop.wm.preferences button-layout 'close,minimize,maximize:'
org.cinnamon.desktop.wm.preferences button-layout 'menu:minimize,maximize,close'
org.cinnamon.desktop.interface gtk-decoration-layout 'menu:minimize,maximize,close'

org.cinnamon.muffin button-layout is the value that changes when I change the title bar layout in cinnamon's settings.

Ah, you're using cinnamon. I didn't realize they used a different settings location. Thanks for investigating what the correct setting is. I'll create a CL today to fetch the value from there when Cinnamon is being used.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0

commit d9bd4752e14b7529d8c3b8a785b1e74a600b2db0
Author: Tim Brown <timbrown@chromium.org>
Date: Thu Dec 14 20:26:34 2017

Read Cinnamon settings for window button layout

Cinnamon uses a different settings schema to specify the window button
layout compared to Gnome. This affects Ubuntu 14.04 using Cinnamon since
my change to use GSettings to read the button layout.

To fix this I had to add an enum value for Cinnamon.

system title bar, and changed window button layout.

Bug:  794376 
Test: Forced the use of the GSettings provider, ran Chrome not using
Change-Id: I2e41df59a71467ac9161751c1fd3e6582c99fdab
Reviewed-on: https://chromium-review.googlesource.com/826027
Commit-Queue: Tim Brown <timbrown@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524161}
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/base/nix/xdg_util.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/base/nix/xdg_util.h
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/base/nix/xdg_util_unittest.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/chrome/browser/password_manager/password_store_factory.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/chrome/browser/printing/printer_manager_dialog_linux.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/chrome/browser/ui/libgtkui/app_indicator_icon.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/chrome/browser/ui/libgtkui/gtk_ui.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/chrome/browser/ui/libgtkui/settings_provider_gsettings.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/chrome/browser/ui/libgtkui/settings_provider_gsettings.h
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/chrome/browser/ui/webui/settings_utils_linux.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/components/os_crypt/key_storage_util_linux.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/net/proxy/proxy_config_service_linux.cc
[modify] https://crrev.com/d9bd4752e14b7529d8c3b8a785b1e74a600b2db0/services/device/wake_lock/power_save_blocker/power_save_blocker_x11.cc

I updated past the fix and can confirm that the button layout on the custom title bar matches the system's again.

Thanks.