Limit the WM_SETCURSOR DefWindowProc artifacts workaround.

This is a refinement of http://crrev.com/186306
Only use a ScopedRedrawLock and DefWindowProc as needed.
Otherwise, mark the message as unhandled for default handling.
( some WM_SETCURSOR calls don't trigger DefWindowProc artifacts )

This is also a speculative fix for http://crbug.com/181282
( http://crrev.com/186306 may have regressed performance )

BUG=89820,97808,113127,178600,181282
TEST=No Win7/Vista/XP opaque-frame (classic theme) painting glitches. Potential fix for MPArch.RWHH_WhiteoutDuration UMA perf regression.
R=sky@chromium.org,ben@chromium.org

Review URL: https://chromiumcodereview.appspot.com/12567010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@187803 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 13 insertions, 4 deletions

diff --git a/ui/views/win/hwnd_message_handler.cc b/ui/views/win/hwnd_message_handler.cc
index 6c0d854..520980d 100644
--- a/ui/views/win/hwnd_message_handler.cc
+++ b/ui/views/win/hwnd_message_handler.cc
@@ -1817,11 +1817,20 @@ LRESULT HWNDMessageHandler::OnReflectedMessage(UINT message,
 LRESULT HWNDMessageHandler::OnSetCursor(UINT message,
                                         WPARAM w_param,
                                         LPARAM l_param) {
-  const LRESULT result = DefWindowProcWithRedrawLock(message, w_param, l_param);
-  // Invalidate the window to paint over any outdated window regions asap, as
-  // using a RedrawLock for WM_SETCURSOR may show content through this window.
-  if (delegate_->IsUsingCustomFrame() && !ui::win::IsAeroGlassEnabled())
+  LRESULT result = 0;
+  // Use a ScopedRedrawLock to avoid weird non-client painting for windows with
+  // custom frames when glass is not enabled. Otherwise, default handling is
+  // sufficient and does not produce the weird non-client painting artifacts.
+  if (delegate_->IsUsingCustomFrame() && !ui::win::IsAeroGlassEnabled() &&
+      LOWORD(l_param) >= HTLEFT && LOWORD(l_param) <= HTBOTTOMRIGHT) {
+    // Prevent classic theme custom frame artifacts on these WM_SETCUROR calls.
+    result = DefWindowProcWithRedrawLock(message, w_param, l_param);
+    // Invalidate the window to paint over any outdated window regions asap, as
+    // using a RedrawLock for WM_SETCURSOR may show content through this window.
     InvalidateRect(hwnd(), NULL, FALSE);
+  } else {
+    SetMsgHandled(FALSE);
+  }
   return result;
 }