Don't check autohide taskbar for WS_EX_TOPMOST when we are querying the autohide state.

chrome/browser/ui/views/chrome_views_delegate.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 "chrome/browser/ui/views/chrome_views_delegate.h"
 
 #include <memory>
 
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 81 matching lines @@
 PrefService* GetPrefsForWindow(const views::Widget* window) {
   Profile* profile = GetProfileForWindow(window);
   if (!profile) {
     // Use local state for windows that have no explicit profile.
     return g_browser_process->local_state();
   }
   return profile->GetPrefs();
 }
 
 #if defined(OS_WIN)
-bool MonitorHasTopmostAutohideTaskbarForEdge(UINT edge, HMONITOR monitor) {
+bool MonitorHasAutohideTaskbarForEdge(UINT edge, HMONITOR monitor) {
   APPBARDATA taskbar_data = { sizeof(APPBARDATA), NULL, 0, edge };
   taskbar_data.hWnd = ::GetForegroundWindow();
 
   // TODO(robliao): Remove ScopedTracker below once crbug.com/462368 is fixed.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "462368 MonitorHasTopmostAutohideTaskbarForEdge"));
+          "462368 MonitorHasAutohideTaskbarForEdge"));
 
   // MSDN documents an ABM_GETAUTOHIDEBAREX, which supposedly takes a monitor
   // rect and returns autohide bars on that monitor.  This sounds like a good
   // idea for multi-monitor systems.  Unfortunately, it appears to not work at
   // least some of the time (erroneously returning NULL) and there's almost no
   // online documentation or other sample code using it that suggests ways to
   // address this problem. We do the following:-
   // 1. Use the ABM_GETAUTOHIDEBAR message. If it works, i.e. returns a valid
   //    window we are done.
   // 2. If the ABM_GETAUTOHIDEBAR message does not work we query the auto hide
@@ skipping 12 matching lines @@
 
     taskbar_data.hWnd = ::FindWindow(L"Shell_TrayWnd", NULL);
     if (!::IsWindow(taskbar_data.hWnd))
       return false;
 
     SHAppBarMessage(ABM_GETTASKBARPOS, &taskbar_data);
     if (taskbar_data.uEdge == edge)
       taskbar = taskbar_data.hWnd;
   }
 
-  if (::IsWindow(taskbar) &&
-      (GetWindowLong(taskbar, GWL_EXSTYLE) & WS_EX_TOPMOST)) {

[ananta, 2016/11/30 02:16:18]

Found this patch from 2+ years ago which had this code. Could not find log
beyond that.

[Peter Kasting, 2016/11/30 07:30:30]

You didn't link to the patch, but I tracked this down further.  (Just gotta be
persistent about tracing through git...)

It was added intentionally here:

https://codereview.chromium.org/66055

See also https://bugs.chromium.org/p/chromium/issues/detail?id=20#c135 , and
maybe https://bugs.chromium.org/p/chromium/issues/detail?id=20#c121 .

I'd like to understand this stuff more closely before OKing removing this.  It
seems like we don't want non-topmost autohide bars to reserve any space, and I'm
worried this would regress that.

[ananta, 2016/11/30 20:37:47]

I found this link on msdn
https://msdn.microsoft.com/en-us/library/windows/desktop/bb787947(v=vs.85).aspx
which states that the option to have a not on top taskbar does not exist
anymore. (From Win 7+) that is. We don't care about vista or XP anymore. With
this it should be safe to remove the topmost check?

+  if (::IsWindow(taskbar)) {
     if (MonitorFromWindow(taskbar, MONITOR_DEFAULTTONEAREST) == monitor)
       return true;
     // In some cases like when the autohide taskbar is on the left of the
     // secondary monitor, the MonitorFromWindow call above fails to return the
     // correct monitor the taskbar is on. We fallback to MonitorFromPoint for
     // the cursor position in that case, which seems to work well.
     POINT cursor_pos = {0};
     GetCursorPos(&cursor_pos);
     if (MonitorFromPoint(cursor_pos, MONITOR_DEFAULTTONEAREST) == monitor)
       return true;
   }
   return false;
 }
 
 int GetAppbarAutohideEdgesOnWorkerThread(HMONITOR monitor) {
   DCHECK(monitor);
 
   int edges = 0;
-  if (MonitorHasTopmostAutohideTaskbarForEdge(ABE_LEFT, monitor))
+  if (MonitorHasAutohideTaskbarForEdge(ABE_LEFT, monitor))
     edges |= views::ViewsDelegate::EDGE_LEFT;
-  if (MonitorHasTopmostAutohideTaskbarForEdge(ABE_TOP, monitor))
+  if (MonitorHasAutohideTaskbarForEdge(ABE_TOP, monitor))
     edges |= views::ViewsDelegate::EDGE_TOP;
-  if (MonitorHasTopmostAutohideTaskbarForEdge(ABE_RIGHT, monitor))
+  if (MonitorHasAutohideTaskbarForEdge(ABE_RIGHT, monitor))
     edges |= views::ViewsDelegate::EDGE_RIGHT;
-  if (MonitorHasTopmostAutohideTaskbarForEdge(ABE_BOTTOM, monitor))
+  if (MonitorHasAutohideTaskbarForEdge(ABE_BOTTOM, monitor))
     edges |= views::ViewsDelegate::EDGE_BOTTOM;
   return edges;
 }
 #endif
 
 #if defined(USE_ASH)
 void ProcessAcceleratorNow(const ui::Accelerator& accelerator) {
   // TODO(afakhry): See if we need here to send the accelerator to the
   // FocusManager of the active window in a follow-up CL.
   ash::WmShell::Get()->accelerator_controller()->Process(accelerator);
@@ skipping 344 matching lines @@
   return ViewsDelegate::GetDialogRelatedButtonHorizontalSpacing();
 }
 
 #if !defined(USE_ASH)
 views::Widget::InitParams::WindowOpacity
 ChromeViewsDelegate::GetOpacityForInitParams(
     const views::Widget::InitParams& params) {
   return views::Widget::InitParams::OPAQUE_WINDOW;
 }
 #endif