MessageBubble which does not require separate window and does not grab input on mouse press event.

chrome/browser/views/info_bubble.cc

Index: chrome/browser/views/info_bubble.cc
diff --git a/chrome/browser/views/info_bubble.cc b/chrome/browser/views/info_bubble.cc
index 41907afb9c1812a07e359eeb0fbe8d09c7e0af5b..d2d6c4a439d70e607a4ec4098b2d428cb3a3a59a 100644
--- a/chrome/browser/views/info_bubble.cc
+++ b/chrome/browser/views/info_bubble.cc
@@ -249,6 +249,9 @@ InfoBubble* InfoBubble::Show(views::Widget* parent,
 }
 
 void InfoBubble::Close() {
+  GetFocusManager()->UnregisterAccelerator(
+      views::Accelerator(base::VKEY_ESCAPE, false, false, false), this);
+
   if (fade_away_on_close_)
     FadeOut();
   else
@@ -298,6 +301,16 @@ InfoBubble::InfoBubble()
       fade_away_on_close_(false) {
 }
 
+#if defined(OS_CHROMEOS)
+InfoBubble::InfoBubble(views::WidgetGtk::Type type)
+    : WidgetGtk(type),
+      border_contents_(NULL),
+      delegate_(NULL),
+      closed_(false),
+      fade_away_on_close_(false) {
+}
+#endif
+
 void InfoBubble::Init(views::Widget* parent,
                       const gfx::Rect& position_relative_to,
                       BubbleBorder::ArrowLocation arrow_location,