Fix tab drag and drop with hi-dpi.

chrome/browser/ui/views/tabs/tab_drag_controller.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/tabs/tab_drag_controller.h"
 
 #include <math.h>
 #include <set>
 
 #include "base/auto_reset.h"
@@ skipping 11 matching lines @@
 #include "chrome/browser/ui/views/tabs/tab.h"
 #include "chrome/browser/ui/views/tabs/tab_strip.h"
 #include "chrome/browser/ui/views/tabs/window_finder.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/user_metrics.h"
 #include "content/public/browser/web_contents.h"
 #include "extensions/browser/extension_function_dispatcher.h"
+#include "ui/compositor/dip_util.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/gestures/gesture_recognizer.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/screen.h"
 #include "ui/views/event_monitor.h"
 #include "ui/views/focus/view_storage.h"
 #include "ui/views/widget/root_view.h"
 #include "ui/views/widget/widget.h"
 
 #if defined(USE_ASH)
@@ skipping 1733 matching lines @@
   TabStrip* owning_tabstrip = attached_tabstrip_ ?
       attached_tabstrip_ : source_tabstrip_;
   views::View* toplevel_view = owning_tabstrip->GetWidget()->GetContentsView();
 
   gfx::Point point = point_in_screen;
   views::View::ConvertPointFromScreen(toplevel_view, &point);
   return point.OffsetFromOrigin();
 }
 
 gfx::NativeWindow TabDragController::GetLocalProcessWindow(
-    const gfx::Point& screen_point,
+    gfx::Point screen_point,
     bool exclude_dragged_view) {
   std::set<gfx::NativeWindow> exclude;
   if (exclude_dragged_view) {
     gfx::NativeWindow dragged_window =
         attached_tabstrip_->GetWidget()->GetNativeWindow();
     if (dragged_window)
       exclude.insert(dragged_window);
   }
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
   // Exclude windows which are pending deletion via Browser::TabStripEmpty().
   // These windows can be returned in the Linux Aura port because the browser
   // window which was used for dragging is not hidden once all of its tabs are
   // attached to another browser window in DragBrowserToNewTabStrip().
   // TODO(pkotwicz): Fix this properly (crbug.com/358482)
   BrowserList* browser_list = BrowserList::GetInstance(
       chrome::HOST_DESKTOP_TYPE_NATIVE);
   for (BrowserList::const_iterator it = browser_list->begin();
        it != browser_list->end(); ++it) {
     if ((*it)->tab_strip_model()->empty())
       exclude.insert((*it)->window()->GetNativeWindow());
   }
 #endif
+
+#if defined(OS_LINUX) && defined(USE_AURA)
+  gfx::NativeWindow dragged_window =
+        attached_tabstrip_->GetWidget()->GetNativeWindow();
+  screen_point = ui::ConvertPointToPixel(dragged_window->layer(), screen_point);
+#endif

[sadrul, 2015/03/20 17:40:24]

This should actually happen in window_finder_x11.cc, right? That would make most
sense, since on Windows, we use DIP in the call to
GetLocalProcessWindowAtPoint(), and so we should also use DIP in the call to
GetLocalProcessWindowAtPoint() on Linux, but convert to pixels before calling
into X11TopmostWindowFinder.

[stapelberg, 2015/03/20 21:48:06]

Done. I really hope you won’t suggest _another_ location to try now :).

[sadrul, 2015/03/20 22:02:03]

Heh no. The new patchset looks good.

We need to make sure that the API we use is mostly consistent across platforms,
and so it's important to make sure we are using the same coordinate-space on
both Windows and Linux for GetLocalProcessWindowAtPoint() (which, in this case,
happens to be DIP).

+
   return GetLocalProcessWindowAtPoint(host_desktop_type_,
                                       screen_point,
                                       exclude);
-
 }