Another attempt at fixing the fullscreen issues with Chrome.

ui/views/win/fullscreen_handler.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/win/fullscreen_handler.h"
 
 #include <memory>
 
 #include "base/logging.h"
 #include "base/win/win_util.h"
 #include "ui/base/win/shell.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/views/win/scoped_fullscreen_visibility.h"
 
 namespace views {
 
 ////////////////////////////////////////////////////////////////////////////////
 // FullscreenHandler, public:
 
 FullscreenHandler::FullscreenHandler() : hwnd_(NULL), fullscreen_(false) {}
 
 FullscreenHandler::~FullscreenHandler() {
 }
 
 void FullscreenHandler::SetFullscreen(bool fullscreen) {
   if (fullscreen_ == fullscreen)
     return;
 
+  if (!task_bar_list_) {

[msw, 2017/07/06 18:32:55]

It's a little odd to init the value here and use it unchecked in the impl
function, but that isn't called anywhere else, so it's probably fine.

[ananta, 2017/07/06 18:44:51]

Thanks. I moved this block to the SetFullscreenImpl() function.

+    HRESULT hr = ::CoCreateInstance(CLSID_TaskbarList, NULL,
+                                    CLSCTX_INPROC_SERVER,
+                                    IID_PPV_ARGS(&task_bar_list_));
+    CHECK(SUCCEEDED(hr));
+  }
+
   SetFullscreenImpl(fullscreen);
 }
 
 gfx::Rect FullscreenHandler::GetRestoreBounds() const {
   return gfx::Rect(saved_window_info_.window_rect);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // FullscreenHandler, private:
 
@@ skipping 25 matching lines @@
 
     // On expand, if we're given a window_rect, grow to it, otherwise do
     // not resize.
     MONITORINFO monitor_info;
     monitor_info.cbSize = sizeof(monitor_info);
     GetMonitorInfo(MonitorFromWindow(hwnd_, MONITOR_DEFAULTTONEAREST),
                    &monitor_info);
     gfx::Rect window_rect(monitor_info.rcMonitor);
     SetWindowPos(hwnd_, NULL, window_rect.x(), window_rect.y(),
                  window_rect.width(), window_rect.height(),
                  SWP_NOZORDER | SWP_NOACTIVATE | SWP_FRAMECHANGED);

[msw, 2017/07/06 18:32:55]

q: Maybe these args let windows enter fullscreen when they are *already
z-ordered below the taskbar*, and by explicitly not changing the activation or
z-order, we leave the fullscreen window behind the taskbar? I'm not sure why we
don't activate or re-order the window when it enters fullscreen. Perhaps we
should consider adjusting/removing SWP_NOZORDER ("Retains the current Z order
(ignores the hWndInsertAfter parameter).") and SWP_NOACTIVATE ("Does not
activate the window. If this flag is not set, the window is activated and moved
to the top of either the topmost or non-topmost group (depending on the setting
of the hWndInsertAfter parameter)."), maybe in a separate CL?

[ananta, 2017/07/06 18:44:51]

The window should be active when we enter this function in most cases. However
if for some reason we lost activation, due to another window on the thread
becoming active, etc we don't want to activate the window again here.

   } else {
     // Reset original window style and size.  The multiple window size/moves
     // here are ugly, but if SetWindowPos() doesn't redraw, the taskbar won't be
     // repainted.  Better-looking methods welcome.
     SetWindowLong(hwnd_, GWL_STYLE, saved_window_info_.style);
     SetWindowLong(hwnd_, GWL_EXSTYLE, saved_window_info_.ex_style);
 
     // On restore, resize to the previous saved rect size.
     gfx::Rect new_rect(saved_window_info_.window_rect);
     SetWindowPos(hwnd_, NULL, new_rect.x(), new_rect.y(), new_rect.width(),
                  new_rect.height(),
                  SWP_NOZORDER | SWP_NOACTIVATE | SWP_FRAMECHANGED);
   }

[msw, 2017/07/06 18:32:55]

nit: add a blank line after this

[ananta, 2017/07/06 18:44:51]

Done.

+  // As per msdn marking the window as fullscreen should ensure that the

[msw, 2017/07/06 18:32:55]

nit: capitalize 'MSDN'

[ananta, 2017/07/06 18:44:51]

Done.

+  // taskbar is moved to the bottom of the Z order when the fullscreen window

[msw, 2017/07/06 18:32:55]

nit: hyphenate 'Z-order'

[ananta, 2017/07/06 18:44:51]

Done.

+  // is activated. If the window is not fullscreen the Shell fallsback to

[msw, 2017/07/06 18:32:55]

nits: comma after 'fullscreen,' and split words 'falls back'

[ananta, 2017/07/06 18:44:51]

Done.

+  // heuristics to determine how the window should be treated, which means
+  // that it could still consider the window as fullscreen. :(
+  task_bar_list_->MarkFullscreenWindow(hwnd_, !!fullscreen);

[msw, 2017/07/06 18:32:55]

As this only moves the taskbar to the bottom of the Z-order *when the window is
active/activated*, perhaps this won't help inactive fullscreen windows (but let
users fix the defect by just clicking the window?). This is another reason to
consider adjusting the SetWindowPos args when entering fullscreen. I'm mostly
just thinking aloud.

[ananta, 2017/07/06 18:44:51]

I think the reason we use SWP_NOACTIVATE is to avoid activating the window again
in case it lost activation before it became fullscreen due to the user clicking
elsewhere. However marking the window fullscreen here would ensure that if the
user switches to the fullscreen window the taskbar would go to the bottom of the
Z-order

 }
 
 }  // namespace views