Enable tooltips for aura.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 09255569f48621af295d661859f23b9ed795c6e1..05491728d722a5880476ea6dd773ce5f32ef4ea0 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -14,6 +14,7 @@
 #include "ui/aura/event.h"
 #include "ui/aura/hit_test.h"
 #include "ui/aura/window.h"
+#include "ui/aura_shell/aura_constants.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/compositor/layer.h"
 
@@ -180,7 +181,8 @@ void RenderWidgetHostViewAura::Destroy() {
 }
 
 void RenderWidgetHostViewAura::SetTooltipText(const string16& tooltip_text) {
-  //NOTIMPLEMENTED();
+  string16* tooltip = new string16(tooltip_text);
+  window_->SetProperty(aura_shell::kTooltipTextKey, tooltip);
 }
 
 BackingStore* RenderWidgetHostViewAura::AllocBackingStore(