Support JavaScript window.moveTo/By() and resizeTo/By() (fixes #698)

Adds new CefDisplayHandler::OnContentsBoundsChange and
CefDisplayHandler::GetRootWindowScreenRect callbacks.

cefclient: Implement the above callbacks and call
CefBrowserHost::NotifyScreenInfoChanged when the root window
bounds change.

cefclient: osr: Use real screen bounds by default. Pass
`--fake-screen-bounds` for the old default behavior.

Load https://tests/window in cefclient for additional
implementation details and usage examples.

tests/cefclient/browser/util_gtk.cc

@@ -30,4 +30,54 @@ ScopedGdkThreadsEnter::~ScopedGdkThreadsEnter() {
   }
 }
 
+CefRect GetWindowBounds(GtkWindow* window, bool include_frame) {
+  GdkWindow* gdk_window = gtk_widget_get_window(GTK_WIDGET(window));
+
+  gint x = 0;
+  gint y = 0;
+  gdk_window_get_origin(gdk_window, &x, &y);
+
+  gint width = 0;
+  gint height = 0;
+  gdk_window_get_geometry(gdk_window, nullptr, nullptr, &width, &height);
+
+  if (include_frame) {
+    GdkRectangle frame_rect = {};
+    gdk_window_get_frame_extents(gdk_window, &frame_rect);
+
+    // This calculation assumes that all added frame height is at the top of the
+    // window, which may be incorrect for some window managers.
+    y -= frame_rect.height - height;
+  }
+
+  return {x, y, width, height};
+}
+
+bool IsWindowMaximized(GtkWindow* window) {
+  GdkWindow* gdk_window = gtk_widget_get_window(GTK_WIDGET(window));
+  gint state = gdk_window_get_state(gdk_window);
+  return (state & GDK_WINDOW_STATE_MAXIMIZED) ? true : false;
+}
+
+void MinimizeWindow(GtkWindow* window) {
+  // Unmaximize the window before minimizing so restore behaves correctly.
+  if (IsWindowMaximized(window)) {
+    gtk_window_unmaximize(window);
+  }
+
+  gtk_window_iconify(window);
+}
+
+void MaximizeWindow(GtkWindow* window) {
+  gtk_window_maximize(window);
+}
+
+void RestoreWindow(GtkWindow* window) {
+  if (IsWindowMaximized(window)) {
+    gtk_window_unmaximize(window);
+  } else {
+    gtk_window_present(window);
+  }
+}
+
 }  // namespace client