Refactor accessible focus ring code so the layers are animation observers.

chrome/browser/chromeos/ui/accessibility_focus_ring_layer.cc

 // Copyright 2014 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 "chrome/browser/chromeos/ui/accessibility_focus_ring_layer.h"
 
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/shell.h"
 #include "base/bind.h"
 #include "third_party/skia/include/core/SkPaint.h"
@@ skipping 89 matching lines @@
 
   gfx::Rect bounds = ring.GetBounds();
   int inset = kGradientWidth;
   bounds.Inset(-inset, -inset, -inset, -inset);
 
   display::Display display =
       display::Screen::GetScreen()->GetDisplayMatching(bounds);
   aura::Window* root_window = ash::Shell::GetInstance()
                                   ->window_tree_host_manager()
                                   ->GetRootWindowForDisplayId(display.id());
-  CreateOrUpdateLayer(root_window, "AccessibilityFocusRing");
-
-  // Update the layer bounds.
-  layer()->SetBounds(bounds);
+  CreateOrUpdateLayer(root_window, "AccessibilityFocusRing", bounds);
 }
 
 void AccessibilityFocusRingLayer::OnPaintLayer(
     const ui::PaintContext& context) {
   ui::PaintRecorder recorder(context, layer()->size());
 
   SkPaint paint;
   paint.setFlags(SkPaint::kAntiAlias_Flag);
   paint.setStyle(SkPaint::kStroke_Style);
   paint.setStrokeWidth(2);
 
   SkPath path;
   gfx::Vector2d offset = layer()->bounds().OffsetFromOrigin();
   const int w = kGradientWidth;
   for (int i = 0; i < w; ++i) {
     paint.setColor(
         SkColorSetARGBMacro(
             255 * (w - i) * (w - i) / (w * w),
             kFocusRingColorRed, kFocusRingColorGreen, kFocusRingColorBlue));
     path = MakePath(ring_, i, offset);
     recorder.canvas()->DrawPath(path, paint);
   }
 }
 
 }  // namespace chromeos