Fix X11DesktopHandler::ActivateWindow on Unity for known user gestures

ui/views/widget/desktop_aura/x11_desktop_handler.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_desktop_handler.h"
 
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
 
 #include "base/message_loop/message_loop.h"
@@ skipping 56 matching lines @@
         ui::WmSupportsHint(atom_cache_.GetAtom("_NET_ACTIVE_WINDOW"));
   }
 }
 
 X11DesktopHandler::~X11DesktopHandler() {
   aura::Env::GetInstance()->RemoveObserver(this);
   if (ui::PlatformEventSource::GetInstance())
     ui::PlatformEventSource::GetInstance()->RemovePlatformEventDispatcher(this);
 }
 
-void X11DesktopHandler::ActivateWindow(::Window window) {
+void X11DesktopHandler::ActivateWindow(::Window window,
+                                       bool for_user_gesture) {
   if ((current_window_ == None || current_window_ == window) &&
       current_window_active_state_ == NOT_ACTIVE) {
     // |window| is most likely still active wrt to the X server. Undo the
     // changes made in DeactivateWindow().
     OnActiveWindowChanged(window, ACTIVE);
 
     // Go through the regular activation path such that calling
     // DeactivateWindow() and ActivateWindow() immediately afterwards results
     // in an active X window.
   }
 
   XRaiseWindow(xdisplay_, window);
 
   if (wm_supports_active_window_) {
     DCHECK_EQ(gfx::GetXDisplay(), xdisplay_);
 
+    // According to
+    // http://standards.freedesktop.org/wm-spec/wm-spec-latest.html#sourceindication
+    // "Some requests from Clients include type of the Client, for example the
+    // _NET_ACTIVE_WINDOW message. Currently the types can be 1 for normal
+    // applications, and 2 for pagers and other Clients that represent direct
+    // user actions (the Window Manager may decide to treat requests from
+    // applications differently than requests that are result of direct user
+    // actions)."
+    //
+    // Normally we set the source indication to 1 (normal application), but when
+    // we know activation is being triggered from a user gesture, then we set it
+    // to 2 so the WM properly prioritizes our request. Without this, Unity on
+    // Ubuntu 14.04 ignores requests to activate a window unless some other
+    // Chrome window is already the active window (see issues 470830 & 411702).
+    long source_indication = for_user_gesture ? 2 : 1;
+
     XEvent xclient;
     memset(&xclient, 0, sizeof(xclient));
     xclient.type = ClientMessage;
     xclient.xclient.window = window;
     xclient.xclient.message_type = atom_cache_.GetAtom("_NET_ACTIVE_WINDOW");
     xclient.xclient.format = 32;
-    xclient.xclient.data.l[0] = 1;  // Specified we are an app.
+    xclient.xclient.data.l[0] = source_indication;
     xclient.xclient.data.l[1] = wm_user_time_ms_;
     xclient.xclient.data.l[2] = None;
     xclient.xclient.data.l[3] = 0;
     xclient.xclient.data.l[4] = 0;
 
     XSendEvent(xdisplay_, x_root_window_, False,
                SubstructureRedirectMask | SubstructureNotifyMask,
                &xclient);
   } else {
     // XRaiseWindow will not give input focus to the window. We now need to ask
@@ skipping 130 matching lines @@
     ui::XMenuList::GetInstance()->MaybeUnregisterMenu(window);
   }
 
   if (event_type == DestroyNotify) {
     // Notify the XForeignWindowManager that |window| has been destroyed.
     ui::XForeignWindowManager::GetInstance()->OnWindowDestroyed(window);
   }
 }
 
 }  // namespace views