Respect GTK3 gtk-titlebar-middle-click setting

When using GTK2, Chromium respects the metacity setting that determines
what to do when the title bar is middle clicked.

There is a similar GTK3 setting for client-side decorated windows,
gtk-titlebar-middle-click, which was ignored by Chromium when using GTK3.
This change makes it respect the GTK3 setting.

Bug: 777821
Change-Id: I4a1cb0af4f7ec4e74e8c9de789f52ea92b1be171
Reviewed-on: https://chromium-review.googlesource.com/743624Reviewed-by: Elliot Glaysher <erg@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512559}

AUTHORS

@@ -560,6 +560,7 @@ Nikhil Bansal <n.bansal@samsung.com>
 Nikhil Sahni <nikhil.sahni@samsung.com>
 Nikita Ofitserov <himikof@gmail.com>
 Niklas Schulze <me@jns.io>
+Nikola Kovacs <nikola.kovacs@gmail.com>
 Nils Schneider <nils@nilsschneider.net>
 Nils Schneider <nils.schneider@gmail.com>
 Ningxin Hu <ningxin.hu@intel.com>

chrome/browser/ui/libgtkui/nav_button_layout_manager_gtk3.cc

@@ -44,7 +44,7 @@ std::string GetDecorationLayoutFromGtkWindow() {
 }  // namespace
 
 NavButtonLayoutManagerGtk3::NavButtonLayoutManagerGtk3(GtkUi* delegate)
-    : delegate_(delegate), signal_id_(0) {
+    : delegate_(delegate), signal_id_(0), signal_id_middle_click_(0) {
   DCHECK(delegate_);
   GtkSettings* settings = gtk_settings_get_default();
   if (GtkVersionCheck(3, 14)) {
@@ -53,6 +53,12 @@ NavButtonLayoutManagerGtk3::NavButtonLayoutManagerGtk3(GtkUi* delegate)
         G_CALLBACK(OnDecorationButtonLayoutChangedThunk), this);
     DCHECK(signal_id_);
     OnDecorationButtonLayoutChanged(settings, nullptr);
+
+    signal_id_middle_click_ =
+        g_signal_connect(settings, "notify::gtk-titlebar-middle-click",
+                         G_CALLBACK(OnMiddleClickActionChangedThunk), this);
+    DCHECK(signal_id_middle_click_);
+    OnMiddleClickActionChanged(settings, nullptr);
   } else if (GtkVersionCheck(3, 10, 3)) {
     signal_id_ = g_signal_connect_after(settings, "notify::gtk-theme-name",
                                         G_CALLBACK(OnThemeChangedThunk), this);
@@ -67,6 +73,9 @@ NavButtonLayoutManagerGtk3::NavButtonLayoutManagerGtk3(GtkUi* delegate)
 NavButtonLayoutManagerGtk3::~NavButtonLayoutManagerGtk3() {
   if (signal_id_)
     g_signal_handler_disconnect(gtk_settings_get_default(), signal_id_);
+  if (signal_id_middle_click_)
+    g_signal_handler_disconnect(gtk_settings_get_default(),
+                                signal_id_middle_click_);
 }
 
 void NavButtonLayoutManagerGtk3::SetWindowButtonOrderingFromGtkLayout(
@@ -84,6 +93,28 @@ void NavButtonLayoutManagerGtk3::OnDecorationButtonLayoutChanged(
       GetGtkSettingsStringProperty(settings, "gtk-decoration-layout"));
 }
 
+void NavButtonLayoutManagerGtk3::OnMiddleClickActionChanged(
+    GtkSettings* settings,
+    GParamSpec* param) {
+  std::string value =
+      GetGtkSettingsStringProperty(settings, "gtk-titlebar-middle-click");
+  GtkUi::NonClientMiddleClickAction action;
+  if (value == "none") {
+    action = views::LinuxUI::MIDDLE_CLICK_ACTION_NONE;
+  } else if (value == "lower") {
+    action = views::LinuxUI::MIDDLE_CLICK_ACTION_LOWER;
+  } else if (value == "minimize") {
+    action = views::LinuxUI::MIDDLE_CLICK_ACTION_MINIMIZE;
+  } else if (value == "toggle-maximize") {
+    action = views::LinuxUI::MIDDLE_CLICK_ACTION_TOGGLE_MAXIMIZE;
+  } else {
+    // Default to no action if the user has explicitly
+    // chosen an action that we don't implement.
+    action = views::LinuxUI::MIDDLE_CLICK_ACTION_NONE;
+  }
+  delegate_->SetNonClientMiddleClickAction(action);
+}
+
 void NavButtonLayoutManagerGtk3::OnThemeChanged(GtkSettings* settings,
                                                 GParamSpec* param) {
   std::string layout = GetDecorationLayoutFromGtkWindow();

chrome/browser/ui/libgtkui/nav_button_layout_manager_gtk3.h

@@ -32,6 +32,12 @@ class NavButtonLayoutManagerGtk3 : public NavButtonLayoutManager {
                      GtkSettings*,
                      GParamSpec*);
 
+  CHROMEG_CALLBACK_1(NavButtonLayoutManagerGtk3,
+                     void,
+                     OnMiddleClickActionChanged,
+                     GtkSettings*,
+                     GParamSpec*);
+
   CHROMEG_CALLBACK_1(NavButtonLayoutManagerGtk3,
                      void,
                      OnThemeChanged,
@@ -42,6 +48,8 @@ class NavButtonLayoutManagerGtk3 : public NavButtonLayoutManager {
 
   unsigned long signal_id_;
 
+  unsigned long signal_id_middle_click_;
+
   DISALLOW_COPY_AND_ASSIGN(NavButtonLayoutManagerGtk3);
 };