Turn off the tip for the sytem tray menu and the app list (ChromeOS).

ui/views/bubble/bubble_delegate.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/bubble/bubble_delegate.h"
 
 #include "ui/base/animation/slide_animation.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/rect.h"
 #include "ui/native_theme/native_theme.h"
@@ skipping 259 matching lines @@
   if (border_widget_)
     border_widget_->SetOpacity(original_opacity_);
   GetWidget()->SetOpacity(original_opacity_);
 }
 
 void BubbleDelegateView::SetAlignment(BubbleBorder::BubbleAlignment alignment) {
   GetBubbleFrameView()->bubble_border()->set_alignment(alignment);
   SizeToContents();
 }
 
+void BubbleDelegateView::SetArrowPaintType(
+    BubbleBorder::ArrowPaintType paint_type) {
+  GetBubbleFrameView()->bubble_border()->set_paint_arrow(paint_type);

[msw, 2013/06/14 21:53:03]

This should probably call SizeToContents(). If the bubble is already showing and
changes from NORMAL/TRANSPARENT (reserving space for the arrow) to NONE (no
space is reserved for the arrow) or vice versa, then the overall bubble position
and widget size would change.

[Mr4D (OOO till 08-26), 2013/06/15 02:16:23]

Done.

+}
+
 bool BubbleDelegateView::AcceleratorPressed(
     const ui::Accelerator& accelerator) {
   if (!close_on_esc() || accelerator.key_code() != ui::VKEY_ESCAPE)
     return false;
   if (fade_animation_.get())
     fade_animation_->Reset();
   GetWidget()->Close();
   return true;
 }
 
@@ skipping 78 matching lines @@
 #if defined(OS_WIN) && !defined(USE_AURA)
 gfx::Rect BubbleDelegateView::GetBubbleClientBounds() const {
   gfx::Rect client_bounds(GetBubbleFrameView()->GetBoundsForClientView());
   client_bounds.Offset(
       border_widget_->GetWindowBoundsInScreen().OffsetFromOrigin());
   return client_bounds;
 }
 #endif
 
 }  // namespace views