Linux Aura: Use managed tab dragging when possible (Reland)

ui/base/x/x11_util.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.
 
 // This file defines utility functions for X11 (Linux only). This code has been
 // ported from XCB since we can't use XCB on Ubuntu while its 32-bit support
 // remains woefully incomplete.
 
 #include "ui/base/x/x11_util.h"
 
@@ skipping 477 matching lines @@
   XChangeProperty(gfx::GetXDisplay(),
                   window,
                   hint_atom,
                   hint_atom,
                   32,
                   PropModeReplace,
                   reinterpret_cast<unsigned char*>(&motif_hints),
                   sizeof(MotifWmHints)/sizeof(long));
 }
 
+void MoveResizeWindowManaged(XID window,
+                             gfx::Point origin,
+                             NetWmMoveResize mode) {
+  XDisplay* display = gfx::GetXDisplay();
+  XAtom message_type = GetAtom("_NET_WM_MOVERESIZE");
+  XEvent event;
+  memset(&event, 0, sizeof(event));
+  event.xclient.type = ClientMessage;
+  event.xclient.display = display;
+  event.xclient.window = window;
+  event.xclient.message_type = message_type;
+  event.xclient.format = 32;
+  event.xclient.data.l[0] = origin.x();
+  event.xclient.data.l[1] = origin.y();
+  event.xclient.data.l[2] = static_cast<long>(mode);
+  event.xclient.data.l[3] =
+      Button1;  // Currently all our managed dragging is done with LMB.
+  event.xclient.data.l[4] = 1;

[Daniel Erat, 2016/10/12 16:13:10]

nit: add something like "// Requested by normal application" at the end of this
line

[Tom (Use chromium acct), 2016/10/12 18:08:27]

Done.

+
+  XSendEvent(display, DefaultRootWindow(display), False,
+             SubstructureRedirectMask | SubstructureNotifyMask, &event);
+  XFlush(display);
+}
+
 bool IsShapeExtensionAvailable() {
   int dummy;
   static bool is_shape_available =
       XShapeQueryExtension(gfx::GetXDisplay(), &dummy, &dummy);
   return is_shape_available;
 }
 
 XID GetX11RootWindow() {
   return DefaultRootWindow(gfx::GetXDisplay());
 }
@@ skipping 1009 matching lines @@
   return colormap_;
 }
 
 #endif
 
 // ----------------------------------------------------------------------------
 // End of x11_util_internal.h
 
 
 }  // namespace ui