Another attempt at fixing the fullscreen issues with Chrome.

ui/views/win/fullscreen_handler.cc

Index: ui/views/win/fullscreen_handler.cc
diff --git a/ui/views/win/fullscreen_handler.cc b/ui/views/win/fullscreen_handler.cc
index 89581d79d06dbae1ebe657ede9aca043725cba7f..df51c3526342a33d57b99228842dbb03f8cfb24e 100644
--- a/ui/views/win/fullscreen_handler.cc
+++ b/ui/views/win/fullscreen_handler.cc
@@ -26,6 +26,13 @@ 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);
 }
 
@@ -85,6 +92,12 @@ void FullscreenHandler::SetFullscreenImpl(bool fullscreen) {
                  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