This affects Windows 7 when switching between Aero and Basic modes.

DCHECK is hit:

[11420:9764:0829/114607.143:FATAL:browser_view.cc(1010)] Check failed: !toolbar_button_provider_.
Backtrace:
        base::debug::StackTrace::StackTrace [0x72E34900+32]
        base::debug::StackTrace::StackTrace [0x72E33F4D+13]
        logging::LogMessage::~LogMessage [0x72E5DEB4+84]
        BrowserView::SetToolbarButtonProvider [0x6E0DD467+91]
        HostedAppButtonContainer::HostedAppButtonContainer [0x6ED3B5F1+969]
        OpaqueBrowserFrameView::OpaqueBrowserFrameView [0x6EBC50D1+853]
        chrome::CreateBrowserNonClientFrameView [0x6E92E0B3+95]
        BrowserFrame::CreateNonClientFrameView [0x6E448BEA+18]
        views::NonClientView::UpdateFrame [0x6C70ED2C+24]
        views::HWNDMessageHandler::PerformDwmTransition [0x6C7158A4+42]
        views::DesktopWindowTreeHostWin::FrameTypeChanged [0x6C733245+17]
        BrowserDesktopWindowTreeHostWin::FrameTypeChanged [0x6EE138D2+12]
        views::DesktopNativeWidgetAura::FrameTypeChanged [0x6C72C5B3+17]
        BrowserView::NativeThemeUpdated [0x6E0DEA66+34]
        ui::NativeTheme::NotifyObservers [0x6A841C89+81]
        gfx::SysColorChangeObserver::OnWndProc [0x728E8280+106]
        base::internal::Invoker<base::internal::BindState<void (__thiscall gfx::SysColorChangeObserver::*)(HWND__ *,unsigned int,unsigned int,long),base::internal::UnretainedWrapper<gfx::SysColorChangeObserver> >,void __cdecl(HWND__ *,unsigned int,unsigned int,lo [0x728E8872+24]
        gfx::SingletonHwndObserver::OnWndProc [0x728EEB80+32]
        gfx::SingletonHwnd::ProcessWindowMessage [0x728EDF97+93]
        gfx::WindowImpl::OnWndProc [0x728EF944+66]
        gfx::WindowImpl::WndProc [0x728EFA10+156]
        base::win::WrappedWindowProc<&gfx::WindowImpl::WndProc> [0x728EF42E+80]
        gapfnScSendMessage [0x750562FA+818]

This is an edge case, but pretty bad. Bumping to P2 (not strictly needed for this milestone). Assigning Alan.

WIP CL screencasts: https://chromium-review.googlesource.com/c/chromium/src/+/1308960

Deleted: before.webm 5.1 MB

	before.webm 5.1 MB View Download

Deleted: after.webm 4.3 MB

	after.webm 4.3 MB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8728d0475b4724115ff89656a333ea6c5b9603b5

commit 8728d0475b4724115ff89656a333ea6c5b9603b5
Author: Alan Cutter <alancutter@chromium.org>
Date: Wed Oct 31 23:53:37 2018

Linux: Fix content settings in PWA titlebar glitch when toggling GTK theme

This CL updates a DCHECK to allow for the BrowserNonClientFrameView
getting recreated when the browser window frame is updated via
NonClientView::UpdateFrame().

This also fixes a UI bug where we don't initialise the content setting
icons properly for PWA windows resulting in uninitialised state after
toggling GTK themes.

Before: https://bugs.chromium.org/p/chromium/issues/attachment?aid=365396&signed_aid=Z-gwLwzrT9I5krg3sUoY7Q==&inline=1
After (ignore Linux screen glitching): https://bugs.chromium.org/p/chromium/issues/attachment?aid=365397&signed_aid=e_kvzb_AGaLLi5zzKY_o7w==&inline=1


Bug:  878639 
Change-Id: I57bd1a6f7f94687a0f95557914f34eda737129ee
Reviewed-on: https://chromium-review.googlesource.com/c/1308960
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604452}
[modify] https://crrev.com/8728d0475b4724115ff89656a333ea6c5b9603b5/chrome/browser/ui/views/frame/browser_view.cc
[modify] https://crrev.com/8728d0475b4724115ff89656a333ea6c5b9603b5/chrome/browser/ui/views/frame/hosted_app_button_container.cc

Tried testing this issue on Windows 7 and Ubuntu 17.10 on the build without fix 70.0.3538.77 and on latest M-72 - 72.0.3598.0 build by following the given steps.

1. Launched Chrome and navigated to https://www.pokedex.org/
2. Open the three dot menu and clicked on "Install Pokedex.org".
3. Waited for the new window to open
4. navigated to chrome://settings and changed theme to GTK+ or Classic.
5. Cannot observe any content settings icon on the title bar on the latest M-72 build.
Attached is the screen cast for reference.

Note: On Windows 7, unable to find the options for switching between Aero and Basic modes, as per comment #1.

alancutter@ Request you to check and confirm if anything is missed from our end in verifying the issue and help us in verifying the fix on the latest M-72 build.

Thanks..

Deleted: 878639-M72.webm 6.7 MB

	878639-M72.webm 6.7 MB View Download

Yep, Windows 7 doesn't have GTK theme options. This looks verified to me.