Fixed tab dragging which was broken on high DPI windows for scales other than 100%.

chrome/browser/ui/views/tabs/window_finder_win.cc

 // Copyright 2014 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/tabs/window_finder.h"
 
 #include "base/win/scoped_gdi_object.h"
 #include "base/win/windows_version.h"
 #include "ui/aura/window.h"
 #include "ui/gfx/screen.h"
+#include "ui/gfx/win/dpi.h"
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host_win.h"
 #include "ui/views/win/hwnd_util.h"
 
 #if defined(USE_ASH)
 aura::Window* GetLocalProcessWindowAtPointAsh(
     const gfx::Point& screen_point,
     const std::set<aura::Window*>& ignore);
 #endif
 
 namespace {
@@ skipping 130 matching lines @@
 
 // Helper class to determine if a particular point contains a window from our
 // process.
 class LocalProcessWindowFinder : public BaseWindowFinder {
  public:
   // Returns the hwnd from our process at screen_loc that is not obscured by
   // another window. Returns NULL otherwise.
   static gfx::NativeWindow GetProcessWindowAtPoint(
       const gfx::Point& screen_loc,
       const std::set<HWND>& ignore) {
-    LocalProcessWindowFinder finder(screen_loc, ignore);
+    gfx::Point screen_loc_in_pixels = gfx::win::DIPToScreenPoint(screen_loc);
+    LocalProcessWindowFinder finder(screen_loc_in_pixels, ignore);

[sky, 2014/04/28 13:44:48]

Can we make LocalProcessWindowFinder and TopMostFinder take DIPs? If not, make
it clearer in descriptions that they take pixels, eg IsTopMostWindowAtPixel..

[ananta, 2014/04/28 18:13:08]

Done. Changed to continue passing in screen coordinates in DIPs. We convert to
pixels in the constructors of these classes.

     // Windows 8 has a window that appears first in the list of iterated
     // windows, yet is not visually on top of everything.
     // TODO(sky): figure out a better way to ignore this window.
     if (finder.result_ &&
         ((base::win::OSInfo::GetInstance()->version() >=
           base::win::VERSION_WIN8) ||
-         TopMostFinder::IsTopMostWindowAtPoint(finder.result_, screen_loc,
+         TopMostFinder::IsTopMostWindowAtPoint(finder.result_,
+                                               screen_loc_in_pixels,
                                                ignore))) {
       return views::DesktopWindowTreeHostWin::GetContentWindowForHWND(
           finder.result_);
     }
     return NULL;
   }
 
  protected:
   virtual bool ShouldStopIterating(HWND hwnd) {
     RECT r;
@@ skipping 41 matching lines @@
     chrome::HostDesktopType host_desktop_type,
     const gfx::Point& screen_point,
     const std::set<aura::Window*>& ignore) {
 #if defined(USE_ASH)
   if (host_desktop_type == chrome::HOST_DESKTOP_TYPE_ASH)
     return GetLocalProcessWindowAtPointAsh(screen_point, ignore);
 #endif
   return LocalProcessWindowFinder::GetProcessWindowAtPoint(
           screen_point, RemapIgnoreSet(ignore));
 }