Dynamically compute tab/frame separator color.

chrome/browser/ui/views/tabs/tab_strip.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 "chrome/browser/ui/views/tabs/tab_strip.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <iterator>
@@ skipping 400 matching lines @@
       canvas->ClipPath(stroke, true);
     Op(stroke, fill, kDifference_SkPathOp, &stroke);
     if (!pressed)
       canvas->sk_canvas()->clipPath(fill, SkRegion::kDifference_Op, true);
     // Now draw the stroke and shadow; the stroke will always be visible, while
     // the shadow will be affected by the clip we set above.
     SkPaint paint;
     paint.setAntiAlias(true);
     const SkColor stroke_color =
         tp->GetColor(ThemeProperties::COLOR_TOOLBAR_TOP_SEPARATOR);
+    const float alpha = SkColorGetA(stroke_color);
+    const SkAlpha shadow_alpha =
+        base::saturated_cast<SkAlpha>(std::round(2.1875f * alpha));
     skia::RefPtr<SkDrawLooper> stroke_looper =
-        CreateShadowDrawLooper(SkColorSetA(stroke_color, 0x8C));
+        CreateShadowDrawLooper(SkColorSetA(stroke_color, shadow_alpha));
     paint.setLooper(stroke_looper.get());
-    paint.setColor(SkColorSetA(stroke_color, pressed ? 0x38 : 0x27));
+    const SkAlpha path_alpha = static_cast<SkAlpha>(
+        std::round((pressed ? 0.875f : 0.609375f) * alpha));
+    paint.setColor(SkColorSetA(stroke_color, path_alpha));
     canvas->DrawPath(stroke, paint);
   } else {
     // Fill.
     gfx::ImageSkia* mask = tp->GetImageSkiaNamed(IDR_NEWTAB_BUTTON_MASK);
     // The canvas and mask have to use the same scale factor.
     const float fill_canvas_scale = mask->HasRepresentation(scale) ?
         scale : ui::GetScaleForScaleFactor(ui::SCALE_FACTOR_100P);
     gfx::Canvas fill_canvas(GetLayoutSize(NEW_TAB_BUTTON), fill_canvas_scale,
                             false);
     PaintFill(pressed, fill_canvas_scale, fill, &fill_canvas);
@@ skipping 125 matching lines @@
       if (custom_image) {
         const bool succeeded = canvas->InitSkPaintForTiling(
             *tp->GetImageSkiaNamed(bg_id), x, y, x_scale * scale, scale, 0, 0,
             &paint);
         DCHECK(succeeded);
       } else {
         paint.setColor(tp->GetColor(ThemeProperties::COLOR_BACKGROUND_TAB));
       }
       const SkColor stroke_color = GetThemeProvider()->GetColor(
           ThemeProperties::COLOR_TOOLBAR_TOP_SEPARATOR);
+      const SkAlpha alpha = static_cast<SkAlpha>(
+          std::round(SkColorGetA(stroke_color) * 0.59375f));
       skia::RefPtr<SkDrawLooper> looper =
-          CreateShadowDrawLooper(SkColorSetA(stroke_color, 0x26));
+          CreateShadowDrawLooper(SkColorSetA(stroke_color, alpha));
       paint.setLooper(looper.get());
       canvas->DrawPath(fill, paint);
     }
 
     // Draw a white highlight on hover.
     SkPaint paint;
     paint.setAntiAlias(true);
     const SkAlpha hover_alpha = static_cast<SkAlpha>(
         hover_animation().CurrentValueBetween(0x00, 0x4D));
     if (hover_alpha != SK_AlphaTRANSPARENT) {
@@ skipping 2295 matching lines @@
           ConvertPointToViewAndGetEventHandler(this, newtab_button_, point);
       if (view)
         return view;
     }
     Tab* tab = FindTabForEvent(point);
     if (tab)
       return ConvertPointToViewAndGetEventHandler(this, tab, point);
   }
   return this;
 }