[GTK] Fix for muted tooltips while sound is playing.

chrome/browser/ui/gtk/tabs/tab_gtk.cc

Index: chrome/browser/ui/gtk/tabs/tab_gtk.cc
diff --git a/chrome/browser/ui/gtk/tabs/tab_gtk.cc b/chrome/browser/ui/gtk/tabs/tab_gtk.cc
index c8a03b083dce365de523d0c4e03e92a610006631..7de94cb5143b8c35c795e66e203502f7a10ff54c 100644
--- a/chrome/browser/ui/gtk/tabs/tab_gtk.cc
+++ b/chrome/browser/ui/gtk/tabs/tab_gtk.cc
@@ -298,12 +298,29 @@ void TabGtk::ContextMenuClosed() {
 }
 
 void TabGtk::UpdateTooltipState() {
+  // Note: This method can be called several times per second for various
+  // reasons (e.g., navigation/loading state changes, tab media indicator
+  // updates, and so on).  However, we must avoid calling the
+  // gtk_widget_set_XXX() methods if there is no actual change in state.
+  // Otherwise, GTK will continuously re-hide *all* tooltips throughout the
+  // browser in response!  http://crbug.com/333002
+
   // Only show the tooltip if the title is truncated.
   if (title_width_ > title_bounds().width()) {
-    gtk_widget_set_tooltip_text(widget(),
-                                base::UTF16ToUTF8(GetTitle()).c_str());
+    const std::string utf8_title = base::UTF16ToUTF8(GetTitle());
+    if (gtk_widget_get_has_tooltip(widget())) {
+      gchar* const current_tooltip = gtk_widget_get_tooltip_text(widget());
+      if (current_tooltip) {
+        const bool title_unchanged = (utf8_title == current_tooltip);
+        g_free(current_tooltip);
+        if (title_unchanged)
+          return;
+      }
+    }
+    gtk_widget_set_tooltip_text(widget(), utf8_title.c_str());
   } else {
-    gtk_widget_set_has_tooltip(widget(), FALSE);
+    if (gtk_widget_get_has_tooltip(widget()))
+      gtk_widget_set_has_tooltip(widget(), FALSE);
   }
 }