1 files changed, 38 insertions, 17 deletions

diff --git a/chrome/views/window.cc b/chrome/views/window.cc
index fb5ce76..d8ea0e9 100644
--- a/chrome/views/window.cc
+++ b/chrome/views/window.cc
@@ -569,8 +569,40 @@ LRESULT Window::OnNCCalcSize(BOOL mode, LPARAM l_param) {
   if (non_client_view_->UseNativeFrame())
     return WidgetWin::OnNCCalcSize(mode, l_param);
 
-  // We need to repaint all when the window bounds change.
-  return WVR_REDRAW;
+  RECT* client_rect = mode ?
+      &reinterpret_cast<NCCALCSIZE_PARAMS*>(l_param)->rgrc[0] :
+      reinterpret_cast<RECT*>(l_param);
+  if (IsMaximized()) {
+    // Make the maximized mode client rect fit the screen exactly, by
+    // subtracting the border Windows automatically adds for maximized mode.
+    int border_thickness = GetSystemMetrics(SM_CXSIZEFRAME);
+    InflateRect(client_rect, -border_thickness, -border_thickness);
+
+    // Find all auto-hide taskbars along the screen edges and adjust in by the
+    // thickness of the auto-hide taskbar on each such edge, so the window isn't
+    // treated as a "fullscreen app", which would cause the taskbars to
+    // disappear.
+    HMONITOR monitor = MonitorFromWindow(GetHWND(), MONITOR_DEFAULTTONEAREST);
+    if (win_util::EdgeHasAutoHideTaskbar(ABE_LEFT, monitor))
+      client_rect->left += win_util::kAutoHideTaskbarThicknessPx;
+    if (win_util::EdgeHasAutoHideTaskbar(ABE_TOP, monitor))
+      client_rect->top += win_util::kAutoHideTaskbarThicknessPx;
+    if (win_util::EdgeHasAutoHideTaskbar(ABE_RIGHT, monitor))
+      client_rect->right -= win_util::kAutoHideTaskbarThicknessPx;
+    if (win_util::EdgeHasAutoHideTaskbar(ABE_BOTTOM, monitor))
+      client_rect->bottom -= win_util::kAutoHideTaskbarThicknessPx;
+
+    // We cannot return WVR_REDRAW when there is nonclient area, or Windows
+    // exhibits bugs where client pixels and child HWNDs are mispositioned by
+    // the width/height of the upper-left nonclient area.
+    return 0;
+  }
+
+  // If the window bounds change, we're going to relayout and repaint anyway.
+  // Returning WVR_REDRAW avoids an extra paint before that of the old client
+  // pixels in the (now wrong) location, and thus makes actions like resizing a
+  // window from the left edge look slightly less broken.
+  return mode ? WVR_REDRAW : 0;
 }
 
 LRESULT Window::OnNCHitTest(const CPoint& point) {
@@ -1099,21 +1131,10 @@ void Window::ResetWindowRegion(bool force) {
   CRect window_rect;
   GetWindowRect(&window_rect);
   HRGN new_region;
-  if (IsMaximized()) {
-    HMONITOR monitor = MonitorFromWindow(GetHWND(), MONITOR_DEFAULTTONEAREST);
-    MONITORINFO mi;
-    mi.cbSize = sizeof mi;
-    GetMonitorInfo(monitor, &mi);
-    CRect work_rect = mi.rcWork;
-    work_rect.OffsetRect(-window_rect.left, -window_rect.top);
-    new_region = CreateRectRgnIndirect(&work_rect);
-  } else {
-    gfx::Path window_mask;
-    non_client_view_->GetWindowMask(gfx::Size(window_rect.Width(),
-                                              window_rect.Height()),
-                                    &window_mask);
-    new_region = window_mask.CreateHRGN();
-  }
+  gfx::Path window_mask;
+  non_client_view_->GetWindowMask(
+      gfx::Size(window_rect.Width(), window_rect.Height()), &window_mask);
+  new_region = window_mask.CreateHRGN();
 
   if (current_rgn_result == ERROR || !EqualRgn(current_rgn, new_region)) {
     // SetWindowRgn takes ownership of the HRGN created by CreateHRGN.