Avoids releasing capture in EndMoveLoop if capture was switched to another window while dragging

ui/views/widget/desktop_aura/x11_whole_screen_move_loop.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 "ui/views/widget/desktop_aura/x11_whole_screen_move_loop.h"
 
 #include <X11/Xlib.h>
 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
 #undef RootWindow
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/aura/env.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/keycodes/keyboard_code_conversion_x.h"
 #include "ui/events/platform/scoped_event_dispatcher.h"
 #include "ui/events/platform/x11/x11_event_source.h"
 #include "ui/gfx/point_conversions.h"
 #include "ui/gfx/screen.h"
 #include "ui/views/controls/image_view.h"
+#include "ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 
 namespace {
 
 // The minimum alpha before we declare a pixel transparent when searching in
 // our source image.
 const uint32 kMinAlpha = 32;
 const unsigned char kDragWidgetOpacity = 0xc0;
@@ skipping 90 matching lines @@
       }
       return ui::POST_DISPATCH_NONE;
     }
     case KeyPress: {
       if (ui::KeyboardCodeFromXKeyEvent(xev) == ui::VKEY_ESCAPE) {
         canceled_ = true;
         EndMoveLoop();
         return ui::POST_DISPATCH_NONE;
       }
       break;
     }

[sadrul, 2014/05/05 19:43:33]

Can we look at the FocusOut event received here to keep track of whether the
capture moved away from the drag-window?

[varkha, 2014/05/06 22:22:12]

Maybe, I was trying though to make this CL simple enough to merge in M35. If you
are looking for the "right thing" then I think
https://codereview.chromium.org/262893002/ is it.

[sadrul, 2014/05/07 14:10:46]

I think keeping track of FocusOut in here would be simpler (the fix would be
entirely contained within this file)

[varkha, 2014/05/07 20:17:54]

Yes, I think I now get what you mean.

     case GenericEvent: {
       ui::EventType type = ui::EventTypeFromNative(xev);
       switch (type) {
         case ui::ET_MOUSE_MOVED:
         case ui::ET_MOUSE_DRAGGED:
         case ui::ET_MOUSE_RELEASED: {
           XEvent xevent = {0};
           if (type == ui::ET_MOUSE_RELEASED) {
             xevent.type = ButtonRelease;
             xevent.xbutton.button = ui::EventButtonFromNative(xev);
@@ skipping 97 matching lines @@
     aura::Env::GetInstance()->set_mouse_button_flags(0);
     should_reset_mouse_flags_ = false;
   }
 
   // TODO(erg): Is this ungrab the cause of having to click to give input focus
   // on drawn out windows? Not ungrabbing here screws the X server until I kill
   // the chrome process.
 
   // Ungrab before we let go of the window.
   XDisplay* display = gfx::GetXDisplay();
-  XUngrabPointer(display, CurrentTime);
+  // Only ungrab pointer if capture was not switched to another window.
+  if (!DesktopWindowTreeHostX11::AnyHostHasCapture())
+    XUngrabPointer(display, CurrentTime);
   XUngrabKeyboard(display, CurrentTime);

[sadrul, 2014/05/05 19:43:33]

I assume we wouldn't want to do this either?

[varkha, 2014/05/06 22:22:12]

Since we still grab the keyboard in this class we also need to ungrab it.
Perhaps we should not grab it either but I wanted this CL to be trivial enough
to possibly be merged in M35.

[sadrul, 2014/05/07 14:10:46]

I meant perhaps we don't want to ungrab the keyboard if we didn't have to ungrab
the pointer.

[varkha, 2014/05/07 20:17:54]

Done.

 
   // Restore the previous dispatcher.
   nested_dispatcher_.reset();
   drag_widget_.reset();
   delegate_->OnMoveLoopEnded();
   XDestroyWindow(display, grab_input_window_);
   grab_input_window_ = None;
 
   in_move_loop_ = false;
   quit_closure_.Run();
@@ skipping 114 matching lines @@
     for (int x = 0; x < in_bitmap->width(); ++x) {
       if (SkColorGetA(in_row[x]) > kMinAlpha)
         return true;
     }
   }
 
   return false;
 }
 
 }  // namespace views