Do not release capture when transferring capture between Chrome windows on Linux

ui/views/widget/desktop_aura/x11_capture_window.cc

+// Copyright 2013 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_capture_window.h"
+
+#include <X11/Xlib.h>
+
+#include "ui/events/platform/x11/x11_event_source.h"
+#include "ui/gfx/x/x11_types.h"
+
+namespace views {
+
+X11CaptureWindow::X11CaptureWindow()
+    : captured_(false),
+      xwindow_(None) {
+  Display* display = gfx::GetXDisplay();
+  XSetWindowAttributes swa;
+  memset(&swa, 0, sizeof(swa));
+  swa.event_mask = ButtonPressMask | ButtonReleaseMask | PointerMotionMask |
+                   LeaveWindowMask | FocusChangeMask | StructureNotifyMask;
+  swa.override_redirect = True;
+  xwindow_ = XCreateWindow(display,
+                           DefaultRootWindow(display),
+                           -100, -100, 10, 10,
+                           0,
+                           CopyFromParent,
+                           InputOnly,
+                           CopyFromParent,
+                           CWEventMask | CWOverrideRedirect,
+                           &swa);
+  XMapRaised(display, xwindow_);
+  ui::X11EventSource::GetInstance()->BlockUntilWindowMapped(xwindow_);
+
+  unsigned int event_mask = PointerMotionMask | ButtonReleaseMask |
+                            ButtonPressMask;
+  int status = XGrabPointer(display, xwindow_, True, event_mask, GrabModeAsync,
+                            GrabModeAsync, None, None, CurrentTime);
+  captured_ = (status == GrabSuccess);
+
+  ui::PlatformEventSource::GetInstance()->
+      AddPlatformEventDispatcher(this);
+}
+
+X11CaptureWindow::~X11CaptureWindow() {
+  ui::PlatformEventSource::GetInstance()->
+      RemovePlatformEventDispatcher(this);
+
+  if (captured_)
+    XUngrabPointer(gfx::GetXDisplay(), CurrentTime);
+  XDestroyWindow(gfx::GetXDisplay(), xwindow_);
+}
+
+bool X11CaptureWindow::CanDispatchEvent(const ui::PlatformEvent& event) {
+  return event->xany.window == xwindow_;
+}
+
+uint32_t X11CaptureWindow::DispatchEvent(const ui::PlatformEvent& event) {
+  // Stop propagation of events which should not be handled by the
+  // DesktopWindowTreeHostX11 which has capture.
+  switch (event->type) {
+    case MotionNotify:
+    case ButtonPress:
+    case ButtonRelease:
+    case FocusOut:
+    case LeaveNotify:
+      return ui::POST_DISPATCH_PERFORM_DEFAULT;
+    default:
+      return ui::POST_DISPATCH_STOP_PROPAGATION;
+  }
+}
+
+}  // namespace views