Use nine image painter to draw tray background

ui/gfx/nine_image_painter.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 "ui/gfx/nine_image_painter.h"
 
 #include <limits>
 
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/core/SkRect.h"
 #include "third_party/skia/include/core/SkScalar.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/safe_integer_conversions.h"
 #include "ui/gfx/image/image_skia_operations.h"
 #include "ui/gfx/insets.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/scoped_canvas.h"
 #include "ui/gfx/skia_util.h"
 
 namespace gfx {
 
 namespace {
 
 // The following functions width and height of the image in pixels for the
 // scale factor in the Canvas.
 int ImageWidthInPixels(const ImageSkia& i, Canvas* c) {
+  if (i.isNull())
+    return 0;
   return i.GetRepresentation(c->image_scale()).pixel_width();
 }
 
 int ImageHeightInPixels(const ImageSkia& i, Canvas* c) {
+  if (i.isNull())
+    return 0;
   return i.GetRepresentation(c->image_scale()).pixel_height();
 }
 
 // Stretches the given image over the specified canvas area.
 void Fill(Canvas* c,
           const ImageSkia& i,
           int x,
           int y,
           int w,
           int h,
@@ skipping 97 matching lines @@
   int i6h = ImageHeightInPixels(images_[6], canvas);
   int i7h = ImageHeightInPixels(images_[7], canvas);
   int i8h = ImageHeightInPixels(images_[8], canvas);
 
   int i4y = std::min(std::min(i0h, i1h), i2h);
   int i4h = height_in_pixels - i4y - std::min(std::min(i6h, i7h), i8h);
 
   SkPaint paint;
   paint.setAlpha(alpha);
 
+  canvas->DrawImageIntInPixel(images_[0], 0, 0, i0w, i0h,
+                              0, 0, i0w, i0h, false, paint);
+
+  if (!images_[1].isNull())
+    Fill(canvas, images_[1], i0w, 0, width_in_pixels - i0w - i2w, i1h, paint);
+
+  if (!images_[2].isNull()) {
+    canvas->DrawImageIntInPixel(
+        images_[2], 0, 0, i2w, i2h, width_in_pixels - i2w,
+        0, i2w, i2h, false, paint);
+  }
+
   if (!images_[4].isNull())
     Fill(canvas, images_[4], i4x, i4y, i4w, i4h, paint);
-  canvas->DrawImageIntInPixel(images_[0], 0, 0, i0w, i0h,
-                              0, 0, i0w, i0h, false, paint);
-  Fill(canvas, images_[1], i0w, 0, width_in_pixels - i0w - i2w, i1h, paint);
-  canvas->DrawImageIntInPixel(images_[2], 0, 0, i2w, i2h, width_in_pixels - i2w,
-                              0, i2w, i2h, false, paint);
-  Fill(canvas, images_[3], 0, i0h, i3w, height_in_pixels - i0h - i6h, paint);
-  Fill(canvas, images_[5], width_in_pixels - i5w, i2h, i5w,
-       height_in_pixels - i2h - i8h, paint);
-  canvas->DrawImageIntInPixel(images_[6], 0, 0, i6w, i6h, 0,
-                              height_in_pixels - i6h, i6w, i6h, false, paint);
-  Fill(canvas, images_[7], i6w, height_in_pixels - i7h,
-       width_in_pixels - i6w - i8w, i7h, paint);
-  canvas->DrawImageIntInPixel(images_[8], 0, 0, i8w, i8h, width_in_pixels - i8w,
-                              height_in_pixels - i8h, i8w, i8h, false, paint);
+
+  if (!images_[3].isNull())
+    Fill(canvas, images_[3], 0, i0h, i3w, height_in_pixels - i0h - i6h, paint);
+
+  if (!images_[5].isNull()) {
+    Fill(canvas, images_[5], width_in_pixels - i5w, i2h, i5w,
+         height_in_pixels - i2h - i8h, paint);
+  }
+
+  if (!images_[6].isNull()) {
+    canvas->DrawImageIntInPixel(images_[6], 0, 0, i6w, i6h, 0,
+                                height_in_pixels - i6h, i6w, i6h, false, paint);
+  }
+
+  if (!images_[7].isNull()) {
+    Fill(canvas, images_[7], i6w, height_in_pixels - i7h,
+         width_in_pixels - i6w - i8w, i7h, paint);
+  }
+
+  if (!images_[8].isNull()) {
+    canvas->DrawImageIntInPixel(
+        images_[8], 0, 0, i8w, i8h, width_in_pixels - i8w,
+        height_in_pixels - i8h, i8w, i8h, false, paint);
+  }
 }
 
 }  // namespace gfx