Fix grabbing capture when the mouse is pressed on Desktop Linux.

ui/base/x/x11_util.h

 // 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.
 
 #ifndef UI_BASE_X_X11_UTIL_H_
 #define UI_BASE_X_X11_UTIL_H_
 
 // This file declares utility functions for X11 (Linux only).
 //
 // These functions do not require the Xlib headers to be included (which is why
@@ skipping 27 matching lines @@
 namespace ui {
 
 // These functions use the default display and this /must/ be called from
 // the UI thread. Thus, they don't support multiple displays.
 
 // These functions cache their results ---------------------------------
 
 // Returns true if the system supports XINPUT2.
 UI_BASE_EXPORT bool IsXInput2Available();
 
+// Grabs the pointer.
+UI_BASE_EXPORT int GrabPointer(XID window, bool owner_events, ::Cursor cursor);
+
+// Ungrabs the pointer.
+UI_BASE_EXPORT void UngrabPointer();

[sadrul, 2014/12/22 21:08:59]

Would it be possible to have something like ScopedGrabPointer? So that the
caller of GrabPointer() receives a ScopedGrabPointer object, and resets it to
ungrab. This makes sure some code doesn't accidentally forget to ungrab, and
doesn't try to ungrab when it doesn't have a grab.

+
 // X shared memory comes in three flavors:
 // 1) No SHM support,
 // 2) SHM putimage,
 // 3) SHM pixmaps + putimage.
 enum SharedMemorySupport {
   SHARED_MEMORY_NONE,
   SHARED_MEMORY_PUTIMAGE,
   SHARED_MEMORY_PIXMAP
 };
 // Return the shared memory type of our X connection.
@@ skipping 317 matching lines @@
 UI_BASE_EXPORT void ResetXCursorCache();
 
 // Returns the cached XcursorImage for |cursor|.
 UI_BASE_EXPORT const XcursorImage* GetCachedXcursorImage(::Cursor cursor);
 
 }  // namespace test
 
 }  // namespace ui
 
 #endif  // UI_BASE_X_X11_UTIL_H_