Constrain native theme menu list arrow to the paint rect

ui/native_theme/native_theme_base.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/native_theme/native_theme_base.h"
 
 #include <limits>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 754 matching lines @@
     button.background_color = menu_list.background_color;
     button.has_border = menu_list.has_border;
     PaintButton(canvas, state, rect, button);
   }
 
   SkPaint paint;
   paint.setColor(SK_ColorBLACK);
   paint.setAntiAlias(true);
   paint.setStyle(SkPaint::kFill_Style);
 
+  static const int arrow_width = 6;
+  static const int arrow_height = 6;

[sadrul, 2015/06/16 14:25:52]

This should be like:

  const int kArrowWidth = 6;
  const int kArrowHeight = 6;

+
+  gfx::Rect arrow(
+    menu_list.arrow_x,
+    menu_list.arrow_y - (arrow_height / 2),
+    arrow_width,
+    arrow_height);
+
+  // Constrain to the paint rect.
+  arrow.Intersect(rect);
+
   SkPath path;
-  path.moveTo(menu_list.arrow_x, menu_list.arrow_y - 3);
-  path.rLineTo(6, 0);
-  path.rLineTo(-3, 6);
+  path.moveTo(arrow.x(), arrow.y());
+  path.lineTo(arrow.right(), arrow.y());
+  path.lineTo(arrow.x() + arrow.width() / 2, arrow.bottom());
   path.close();
   canvas->drawPath(path, paint);
 }
 
 void NativeThemeBase::PaintMenuPopupBackground(
     SkCanvas* canvas,
     const gfx::Size& size,
     const MenuBackgroundExtraParams& menu_background) const {
   canvas->drawColor(kMenuPopupBackgroundColor, SkXfermode::kSrc_Mode);
 }
@@ skipping 292 matching lines @@
   SkScalar min_diff = Clamp((hsv1[1] + hsv2[1]) * 1.2f, 0.28f, 0.5f);
   SkScalar diff = Clamp(fabs(hsv1[2] - hsv2[2]) / 2, min_diff, 0.5f);
 
   if (hsv1[2] + hsv2[2] > 1.0)
     diff = -diff;
 
   return SaturateAndBrighten(hsv2, -0.2f, diff);
 }
 
 }  // namespace ui