Avoid applying alpha twice in RenderText.

ui/gfx/render_text.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/render_text.h"
 
 #include <limits.h>
 
 #include <algorithm>
 #include <climits>
@@ skipping 126 matching lines @@
   colors->push_back(c1);
 }
 
 // Creates a SkShader to fade the text, with |left_part| specifying the left
 // fade effect, if any, and |right_part| specifying the right fade effect.
 skia::RefPtr<SkShader> CreateFadeShader(const FontList& font_list,
                                         const Rect& text_rect,
                                         const Rect& left_part,
                                         const Rect& right_part,
                                         SkColor color) {
+  // The shader should only specify transparency of the fade itself, not the
+  // original transparency, which will be applied by the actual renderer.
+  DCHECK_EQ(SkColorGetA(color), static_cast<uint8_t>(0xff));
+
   // In general, fade down to 0 alpha.  But when the available width is less
   // than four characters, linearly ramp up the fade target alpha to as high as
   // 20% at zero width.  This allows the user to see the last faded characters a
   // little better when there are only a few characters shown.
   const float width_fraction =
       text_rect.width() / static_cast<float>(font_list.GetExpectedTextWidth(4));
   const SkAlpha kAlphaAtZeroWidth = 51;
   const SkAlpha alpha = (width_fraction < 1) ?
       static_cast<SkAlpha>(round((1 - width_fraction) * kAlphaAtZeroWidth)) : 0;
   const SkColor fade_color = SkColorSetA(color, alpha);
@@ skipping 1069 matching lines @@
     right_part.Inset(solid_part.width() - gradient_width, 0, 0, 0);
     solid_part.Inset(0, 0, gradient_width, 0);
   }
 
   Rect text_rect = display_rect();
   text_rect.Inset(GetAlignmentOffset(0).x(), 0, 0, 0);
 
   // TODO(msw): Use the actual text colors corresponding to each faded part.
   skia::RefPtr<SkShader> shader =
       CreateFadeShader(font_list(), text_rect, left_part, right_part,
-                       colors_.breaks().front().second);
+                       SkColorSetA(colors_.breaks().front().second, 0xff));
   if (shader)
     renderer->SetShader(shader.get());
 }
 
 void RenderText::ApplyTextShadows(internal::SkiaTextRenderer* renderer) {
   skia::RefPtr<SkDrawLooper> looper = CreateShadowDrawLooper(shadows_);
   renderer->SetDrawLooper(looper.get());
 }
 
 base::i18n::TextDirection RenderText::GetTextDirection(
@@ skipping 297 matching lines @@
 
   SetDisplayOffset(display_offset_.x() + delta_x);
 }
 
 void RenderText::DrawSelection(Canvas* canvas) {
   for (const Rect& s : GetSubstringBounds(selection()))
     canvas->FillRect(s, selection_background_focused_color_);
 }
 
 }  // namespace gfx