--- a/gfx/src/nsThemeConstants.h
+++ b/gfx/src/nsThemeConstants.h
@@ -281,8 +281,10 @@
 
 // moz-apperance style used in setting proper glass margins
 #define NS_THEME_WIN_EXCLUDE_GLASS                         242
 
 #define NS_THEME_MAC_VIBRANCY_LIGHT                        243
 #define NS_THEME_MAC_VIBRANCY_DARK                         244
 #define NS_THEME_MAC_DISCLOSURE_BUTTON_OPEN                245
 #define NS_THEME_MAC_DISCLOSURE_BUTTON_CLOSED              246
+
+#define NS_THEME_GTK_INFO_BAR                              247

--- a/layout/style/nsCSSKeywordList.h
+++ b/layout/style/nsCSSKeywordList.h
@@ -66,16 +66,18 @@ CSS_KEY(-moz-fieldtext, _moz_fieldtext)
 CSS_KEY(-moz-fit-content, _moz_fit_content)
 CSS_KEY(-moz-fixed, _moz_fixed)
 CSS_KEY(-moz-grabbing, _moz_grabbing)
 CSS_KEY(-moz-grab, _moz_grab)
 CSS_KEY(-moz-grid-group, _moz_grid_group)
 CSS_KEY(-moz-grid-line, _moz_grid_line)
 CSS_KEY(-moz-grid, _moz_grid)
 CSS_KEY(-moz-groupbox, _moz_groupbox)
+CSS_KEY(-moz-gtk-info-bar, _moz_gtk_info_bar)
+CSS_KEY(-moz-gtk-info-bar-text, _moz_gtk_info_bar_text)
 CSS_KEY(-moz-hidden-unscrollable, _moz_hidden_unscrollable)
 CSS_KEY(-moz-hyperlinktext, _moz_hyperlinktext)
 CSS_KEY(-moz-html-cellhighlight, _moz_html_cellhighlight)
 CSS_KEY(-moz-html-cellhighlighttext, _moz_html_cellhighlighttext)
 CSS_KEY(-moz-image-rect, _moz_image_rect)
 CSS_KEY(-moz-info, _moz_info)
 CSS_KEY(-moz-inline-box, _moz_inline_box)
 CSS_KEY(-moz-inline-grid, _moz_inline_grid)

--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -740,16 +740,17 @@ const KTableValue nsCSSProps::kAppearanc
   eCSSKeyword__moz_window_button_restore,     NS_THEME_WINDOW_BUTTON_RESTORE,
   eCSSKeyword__moz_window_button_box,         NS_THEME_WINDOW_BUTTON_BOX,
   eCSSKeyword__moz_window_button_box_maximized, NS_THEME_WINDOW_BUTTON_BOX_MAXIMIZED,
   eCSSKeyword__moz_win_exclude_glass,         NS_THEME_WIN_EXCLUDE_GLASS,
   eCSSKeyword__moz_mac_vibrancy_light,        NS_THEME_MAC_VIBRANCY_LIGHT,
   eCSSKeyword__moz_mac_vibrancy_dark,         NS_THEME_MAC_VIBRANCY_DARK,
   eCSSKeyword__moz_mac_disclosure_button_open,   NS_THEME_MAC_DISCLOSURE_BUTTON_OPEN,
   eCSSKeyword__moz_mac_disclosure_button_closed, NS_THEME_MAC_DISCLOSURE_BUTTON_CLOSED,
+  eCSSKeyword__moz_gtk_info_bar,              NS_THEME_GTK_INFO_BAR,
   eCSSKeyword_UNKNOWN,-1
 };
 
 const KTableValue nsCSSProps::kBackfaceVisibilityKTable[] = {
   eCSSKeyword_visible, NS_STYLE_BACKFACE_VISIBILITY_VISIBLE,
   eCSSKeyword_hidden, NS_STYLE_BACKFACE_VISIBILITY_HIDDEN,
   eCSSKeyword_UNKNOWN,-1
 };
@@ -955,16 +956,17 @@ const KTableValue nsCSSProps::kColorKTab
   eCSSKeyword__moz_eventreerow, LookAndFeel::eColorID__moz_eventreerow,
   eCSSKeyword__moz_field, LookAndFeel::eColorID__moz_field,
   eCSSKeyword__moz_fieldtext, LookAndFeel::eColorID__moz_fieldtext,
   eCSSKeyword__moz_default_background_color, NS_COLOR_MOZ_DEFAULT_BACKGROUND_COLOR,
   eCSSKeyword__moz_default_color, NS_COLOR_MOZ_DEFAULT_COLOR,
   eCSSKeyword__moz_dialog, LookAndFeel::eColorID__moz_dialog,
   eCSSKeyword__moz_dialogtext, LookAndFeel::eColorID__moz_dialogtext,
   eCSSKeyword__moz_dragtargetzone, LookAndFeel::eColorID__moz_dragtargetzone,
+  eCSSKeyword__moz_gtk_info_bar_text, LookAndFeel::eColorID__moz_gtk_info_bar_text,
   eCSSKeyword__moz_hyperlinktext, NS_COLOR_MOZ_HYPERLINKTEXT,
   eCSSKeyword__moz_html_cellhighlight, LookAndFeel::eColorID__moz_html_cellhighlight,
   eCSSKeyword__moz_html_cellhighlighttext, LookAndFeel::eColorID__moz_html_cellhighlighttext,
   eCSSKeyword__moz_mac_buttonactivetext, LookAndFeel::eColorID__moz_mac_buttonactivetext,
   eCSSKeyword__moz_mac_chrome_active, LookAndFeel::eColorID__moz_mac_chrome_active,
   eCSSKeyword__moz_mac_chrome_inactive, LookAndFeel::eColorID__moz_mac_chrome_inactive,
   eCSSKeyword__moz_mac_defaultbuttontext, LookAndFeel::eColorID__moz_mac_defaultbuttontext,
   eCSSKeyword__moz_mac_focusring, LookAndFeel::eColorID__moz_mac_focusring,

--- a/widget/LookAndFeel.h
+++ b/widget/LookAndFeel.h
@@ -169,16 +169,19 @@ public:
     // but it is used regularly within Windows and the Gnome DE on Dialog and
     // Window colors.
     eColorID__moz_nativehyperlinktext,
 
     // Combo box widgets
     eColorID__moz_comboboxtext,
     eColorID__moz_combobox,
 
+    // GtkInfoBar
+    eColorID__moz_gtk_info_bar_text,
+
     // keep this one last, please
     eColorID_LAST_COLOR
   };
 
   // When modifying this list, also modify nsXPLookAndFeel::sIntPrefs
   // in widget/xpwidgts/nsXPLookAndFeel.cpp.
   enum IntID {
     // default, may be overriden by OS

--- a/widget/gtk/gtk3drawing.c
+++ b/widget/gtk/gtk3drawing.c
@@ -56,16 +56,17 @@ static GtkTreeViewColumn* gMiddleTreeVie
 static GtkWidget* gTreeHeaderCellWidget;
 static GtkWidget* gTreeHeaderSortArrowWidget;
 static GtkWidget* gExpanderWidget;
 static GtkWidget* gToolbarSeparatorWidget;
 static GtkWidget* gMenuSeparatorWidget;
 static GtkWidget* gHPanedWidget;
 static GtkWidget* gVPanedWidget;
 static GtkWidget* gScrolledWindowWidget;
+static GtkWidget* gInfoBar;
 
 static style_prop_t style_prop_func;
 static gboolean have_arrow_scaling;
 static gboolean checkbox_check_state;
 static gboolean notebook_has_tab_gap;
 static gboolean is_initialized;
 
 #define ARROW_UP      0
@@ -353,16 +354,25 @@ ensure_combo_box_widgets()
 
     /* We don't test the validity of gComboBoxSeparatorWidget since there
      * is none when "appears-as-list" = TRUE or "cell-view" = FALSE; if it
      * is invalid we just won't paint it. */
 
     return MOZ_GTK_SUCCESS;
 }
 
+static void
+ensure_info_bar()
+{
+  if (!gInfoBar) {
+      gInfoBar = gtk_info_bar_new();
+      setup_widget_prototype(gInfoBar);
+  }
+}
+
 /* We need to have pointers to the inner widgets (entry, button, arrow) of
  * the ComboBoxEntry to get the correct rendering from theme engines which
  * special cases their look. Since the inner layout can change, we ask GTK
  * to NULL our pointers when they are about to become invalid because the
  * corresponding widgets don't exist anymore. It's the role of
  * g_object_add_weak_pointer().
  * Note that if we don't find the inner widgets (which shouldn't happen), we
  * fallback to use generic "non-inner" widgets, and they don't need that kind
@@ -2598,16 +2608,39 @@ moz_gtk_check_menu_item_paint(cairo_t *c
     } else {
       gtk_render_check(style, cr, x, y, indicator_size, indicator_size);
     }
     gtk_style_context_restore(style);
 
     return MOZ_GTK_SUCCESS;
 }
 
+static gint
+moz_gtk_info_bar_paint(cairo_t *cr, GdkRectangle* rect,
+                       GtkWidgetState* state)
+{
+    GtkStateFlags state_flags = GetStateFlagsFromGtkWidgetState(state);
+    GtkStyleContext *style;
+    ensure_info_bar();
+
+    style = gtk_widget_get_style_context(gInfoBar);
+    gtk_style_context_save(style);
+
+    gtk_style_context_set_state(style, state_flags);
+    gtk_style_context_add_class(style, GTK_STYLE_CLASS_INFO);
+
+    gtk_render_background(style, cr, rect->x, rect->y, rect->width,
+                          rect->height);
+    gtk_render_frame(style, cr, rect->x, rect->y, rect->width, rect->height);
+
+    gtk_style_context_restore(style);
+
+    return MOZ_GTK_SUCCESS;
+}
+
 static void
 moz_gtk_add_style_border(GtkStyleContext* style,
                          gint* left, gint* top, gint* right, gint* bottom)
 {
     GtkBorder border;
 
     gtk_style_context_get_border(style, 0, &border);
 
@@ -2824,16 +2857,20 @@ moz_gtk_get_widget_border(GtkThemeWidget
                 w = gCheckMenuItemWidget;
             }
 
             *left = *top = *right = *bottom = gtk_container_get_border_width(GTK_CONTAINER(w));
             moz_gtk_add_style_padding(gtk_widget_get_style_context(w),
                                       left, top, right, bottom);
             return MOZ_GTK_SUCCESS;
         }
+    case MOZ_GTK_INFO_BAR:
+        ensure_info_bar();
+        w = gInfoBar;
+        break;
     /* These widgets have no borders, since they are not containers. */
     case MOZ_GTK_CHECKBUTTON_LABEL:
     case MOZ_GTK_RADIOBUTTON_LABEL:
     case MOZ_GTK_SPLITTER_HORIZONTAL:
     case MOZ_GTK_SPLITTER_VERTICAL:
     case MOZ_GTK_CHECKBUTTON:
     case MOZ_GTK_RADIOBUTTON:
     case MOZ_GTK_SCROLLBAR_BUTTON:
@@ -3305,16 +3342,19 @@ moz_gtk_widget_paint(GtkThemeWidgetType 
         return moz_gtk_vpaned_paint(cr, rect, state);
         break;
     case MOZ_GTK_SPLITTER_VERTICAL:
         return moz_gtk_hpaned_paint(cr, rect, state);
         break;
     case MOZ_GTK_WINDOW:
         return moz_gtk_window_paint(cr, rect, direction);
         break;
+    case MOZ_GTK_INFO_BAR:
+        return moz_gtk_info_bar_paint(cr, rect, state);
+        break;
     default:
         g_warning("Unknown widget type: %d", widget);
     }
 
     return MOZ_GTK_UNKNOWN_WIDGET;
 }
 
 GtkWidget* moz_gtk_get_scrollbar_widget(void)

--- a/widget/gtk/gtkdrawing.h
+++ b/widget/gtk/gtkdrawing.h
@@ -180,17 +180,19 @@ typedef enum {
   MOZ_GTK_CHECKMENUITEM,
   MOZ_GTK_RADIOMENUITEM,
   MOZ_GTK_MENUSEPARATOR,
   /* Paints a GtkVPaned separator */
   MOZ_GTK_SPLITTER_HORIZONTAL,
   /* Paints a GtkHPaned separator */
   MOZ_GTK_SPLITTER_VERTICAL,
   /* Paints the background of a window, dialog or page. */
-  MOZ_GTK_WINDOW
+  MOZ_GTK_WINDOW,
+  /* Paints a GtkInfoBar, for notifications. */
+  MOZ_GTK_INFO_BAR
 } GtkThemeWidgetType;
 
 /*** General library functions ***/
 /**
  * Initializes the drawing library.  You must call this function
  * prior to using any other functionality.
  * returns: MOZ_GTK_SUCCESS if there were no errors
  *          MOZ_GTK_UNSAFE_THEME if the current theme engine is known

--- a/widget/gtk/mozgtk/mozgtk.c
+++ b/widget/gtk/mozgtk/mozgtk.c
@@ -249,16 +249,18 @@ STUB(gtk_im_context_focus_out)
 STUB(gtk_im_context_get_preedit_string)
 STUB(gtk_im_context_reset)
 STUB(gtk_im_context_set_client_window)
 STUB(gtk_im_context_set_cursor_location)
 STUB(gtk_im_context_set_surrounding)
 STUB(gtk_im_context_simple_new)
 STUB(gtk_im_multicontext_get_type)
 STUB(gtk_im_multicontext_new)
+STUB(gtk_info_bar_get_type)
+STUB(gtk_info_bar_new)
 STUB(gtk_init)
 STUB(gtk_invisible_new)
 STUB(gtk_key_snooper_install)
 STUB(gtk_key_snooper_remove)
 STUB(gtk_label_get_type)
 STUB(gtk_label_new)
 STUB(gtk_label_set_markup)
 STUB(gtk_link_button_new)

--- a/widget/gtk/nsLookAndFeel.cpp
+++ b/widget/gtk/nsLookAndFeel.cpp
@@ -409,16 +409,23 @@ nsLookAndFeel::NativeGetColor(ColorID aI
         break;
 #endif
     case eColorID__moz_menubartext:
         aColor = sMenuBarText;
         break;
     case eColorID__moz_menubarhovertext:
         aColor = sMenuBarHoverText;
         break;
+    case eColorID__moz_gtk_info_bar_text:
+#if (MOZ_WIDGET_GTK == 3)
+        aColor = sInfoBarText;
+#else
+        aColor = sInfoText;
+#endif
+        break;
     default:
         /* default color is BLACK */
         aColor = 0;
         res    = NS_ERROR_FAILURE;
         break;
     }
 
     return res;
@@ -1188,16 +1195,27 @@ nsLookAndFeel::Init()
 
     // TODO GTK3 - update sFrameOuterLightBorder 
     // for GTK_BORDER_STYLE_INSET/OUTSET/GROVE/RIDGE border styles (Bug 978172).
     style = gtk_widget_get_style_context(frame);
     gtk_style_context_get_border_color(style, GTK_STATE_FLAG_NORMAL, &color);
     sFrameInnerDarkBorder = sFrameOuterLightBorder = GDK_RGBA_TO_NS_RGBA(color);
 
     gtk_widget_path_free(path);
+
+    // GtkInfoBar
+    path = gtk_widget_path_new();
+    gtk_widget_path_append_type(path, GTK_TYPE_WINDOW);
+    gtk_widget_path_append_type(path, GTK_TYPE_INFO_BAR);
+    style = create_context(path);
+    gtk_style_context_add_class(style, GTK_STYLE_CLASS_INFO);
+    gtk_style_context_get_color(style, GTK_STATE_FLAG_NORMAL, &color);
+    sInfoBarText = GDK_RGBA_TO_NS_RGBA(color);
+    g_object_unref(style);
+    gtk_widget_path_free(path);
 #endif
     // Some themes have a unified menu bar, and support window dragging on it
     gboolean supports_menubar_drag = FALSE;
     GParamSpec *param_spec =
         gtk_widget_class_find_style_property(GTK_WIDGET_GET_CLASS(menuBar),
                                              "window-dragging");
     if (param_spec) {
         if (g_type_is_a(G_PARAM_SPEC_VALUE_TYPE(param_spec), G_TYPE_BOOLEAN)) {

--- a/widget/gtk/nsLookAndFeel.h
+++ b/widget/gtk/nsLookAndFeel.h
@@ -73,16 +73,19 @@ protected:
     nscolor sComboBoxBackground;
     nscolor sMozFieldText;
     nscolor sMozFieldBackground;
     nscolor sMozWindowText;
     nscolor sMozWindowBackground;
     nscolor sTextSelectedText;
     nscolor sTextSelectedBackground;
     nscolor sMozScrollbar;
+#if (MOZ_WIDGET_GTK == 3)
+    nscolor sInfoBarText;
+#endif
     char16_t sInvisibleCharacter;
     float   sCaretRatio;
     bool    sMenuSupportsDrag;
 
     void Init();
 };
 
 #endif

--- a/widget/gtk/nsNativeThemeGTK.cpp
+++ b/widget/gtk/nsNativeThemeGTK.cpp
@@ -679,16 +679,19 @@ nsNativeThemeGTK::GetGtkWidgetAndState(u
     break;
   case NS_THEME_RADIOMENUITEM:
     aGtkWidgetType = MOZ_GTK_RADIOMENUITEM;
     break;
   case NS_THEME_WINDOW:
   case NS_THEME_DIALOG:
     aGtkWidgetType = MOZ_GTK_WINDOW;
     break;
+  case NS_THEME_GTK_INFO_BAR:
+    aGtkWidgetType = MOZ_GTK_INFO_BAR;
+    break;
   default:
     return false;
   }
 
   return true;
 }
 
 #if (MOZ_WIDGET_GTK == 2)
@@ -1768,16 +1771,19 @@ nsNativeThemeGTK::ThemeSupportsWidget(ns
   case NS_THEME_MENUITEM:
   case NS_THEME_MENUARROW:
   case NS_THEME_MENUSEPARATOR:
   case NS_THEME_CHECKMENUITEM:
   case NS_THEME_RADIOMENUITEM:
   case NS_THEME_SPLITTER:
   case NS_THEME_WINDOW:
   case NS_THEME_DIALOG:
+#if (MOZ_WIDGET_GTK == 3)
+  case NS_THEME_GTK_INFO_BAR:
+#endif
     return !IsWidgetStyled(aPresContext, aFrame, aWidgetType);
 
   case NS_THEME_DROPDOWN_BUTTON:
     if (aFrame && aFrame->GetWritingMode().IsVertical()) {
       return false;
     }
     // "Native" dropdown buttons cause padding and margin problems, but only
     // in HTML so allow them in XUL.