ui/gfx: remove redundant 32x32 DashedRect drawing if a dest rect is empty

ui/gfx/canvas.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/gfx/canvas.h"
 
 #include <cmath>
 #include <limits>
 
 #include "base/i18n/rtl.h"
@@ skipping 113 matching lines @@
   // of the bitmap.
   const SkISize size = canvas_->getDeviceSize();
   SkBitmap result;
   result.allocN32Pixels(size.width(), size.height());
 
   canvas_->readPixels(&result, 0, 0);
   return ImageSkiaRep(result, image_scale_);
 }
 
 void Canvas::DrawDashedRect(const Rect& rect, SkColor color) {
+  if (rect.IsEmpty())
+    return;
   // Create a 2D bitmap containing alternating on/off pixels - we do this
   // so that you never get two pixels of the same color around the edges
   // of the focus rect (this may mean that opposing edges of the rect may
   // have a dot pattern out of phase to each other).
   static SkColor last_color;
   static SkBitmap* dots = NULL;
   if (!dots || last_color != color) {
     int col_pixels = 32;
     int row_pixels = 32;
 
@@ skipping 485 matching lines @@
   SkPaint p(paint);
   p.setFilterLevel(filter ? SkPaint::kLow_FilterLevel
                           : SkPaint::kNone_FilterLevel);
   p.setShader(shader.get());
 
   // The rect will be filled by the bitmap.
   canvas_->drawRect(dest_rect, p);
 }
 
 }  // namespace gfx