Use the MonitorFromPoint API for the cursor position to cover cases where the MonitorFromWindow API…

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 "base/memory/scoped_ptr.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
@@ skipping 108 matching lines @@
       return false;
 
     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;
   }
-  return ::IsWindow(taskbar) &&
-      (MonitorFromWindow(taskbar, MONITOR_DEFAULTTONULL) == monitor) &&
-      (GetWindowLong(taskbar, GWL_EXSTYLE) & WS_EX_TOPMOST);
+
+  if (::IsWindow(taskbar) &&
+      (GetWindowLong(taskbar, GWL_EXSTYLE) & WS_EX_TOPMOST)) {
+    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))
     edges |= views::ViewsDelegate::EDGE_LEFT;
   if (MonitorHasTopmostAutohideTaskbarForEdge(ABE_TOP, monitor))
     edges |= views::ViewsDelegate::EDGE_TOP;
@@ skipping 351 matching lines @@
   return content::BrowserThread::GetBlockingPool();
 }
 
 #if !defined(USE_ASH)
 views::Widget::InitParams::WindowOpacity
 ChromeViewsDelegate::GetOpacityForInitParams(
     const views::Widget::InitParams& params) {
   return views::Widget::InitParams::OPAQUE_WINDOW;
 }
 #endif