Tone down the hover effect on mousing over background tabs.

chrome/browser/ui/views/tabs/tab.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.h"
 
 #include <stddef.h>
 #include <limits>
 #include <utility>
 
@@ skipping 1325 matching lines @@
                                         bool is_active,
                                         int fill_id,
                                         bool has_custom_image,
                                         int y_offset) {
   gfx::ImageSkia* fill_image = GetThemeProvider()->GetImageSkiaNamed(fill_id);
   // The tab image needs to be lined up with the background image
   // so that it feels partially transparent.  These offsets represent the tab
   // position within the frame background image.
   const int x_offset = GetMirroredX() + background_offset_.x();
 
-  const SkScalar radius = SkFloatToScalar(width() / 3.f);
-  const bool draw_hover =
-      !is_active && hover_controller_.ShouldDraw() && radius > 0;
+  const SkScalar kMinHoverRadius = 16;
+  const SkScalar radius =
+      std::max(SkFloatToScalar(width() / 4.f), kMinHoverRadius);
+  const bool draw_hover = !is_active && hover_controller_.ShouldDraw();
   SkPoint hover_location(PointToSkPoint(hover_controller_.location()));
   const SkAlpha hover_alpha = hover_controller_.GetAlpha();
 
   if (ui::MaterialDesignController::IsModeMaterial()) {
     gfx::ScopedCanvas scoped_canvas(canvas);
     const float scale = canvas->UndoDeviceScaleFactor();
 
     // Draw the fill.
     SkPath fill;
     GetFillPath(scale, &fill);
@@ skipping 406 matching lines @@
                          const gfx::ImageSkia& image) {
   DCHECK_NE(scale_factor, ui::SCALE_FACTOR_NONE);
   ImageCacheEntry entry;
   entry.resource_id = resource_id;
   entry.scale_factor = scale_factor;
   entry.image = image;
   image_cache_->push_front(entry);
   if (image_cache_->size() > kMaxImageCacheSize)
     image_cache_->pop_back();
 }