Distill the concept of the "tab top exclusion region", an area inside the tab

chrome/browser/ui/views/layout_constants.cc

 // Copyright 2015 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/layout_constants.h"
 
 #include "base/logging.h"
 #include "ui/base/resource/material_design/material_design_controller.h"
 
 int GetLayoutConstant(LayoutConstant constant) {
   const int kFindBarVerticalOffset[] = {1, 6, 6};
   const int kIconLabelViewInternalPadding[] = {3, 2, 2};
   const int kIconLabelViewTrailingPadding[] = {2, 8, 8};
   const int kLocationBarBorderThickness[] = {2, 1, 1};
   const int kLocationBarBubbleHorizontalPadding[] = {1, 4, 4};
   const int kLocationBarBubbleVerticalPadding[] = {1, 4, 4};
   const int kLocationBarHeight[] = {0, 28, 32};
   const int kLocationBarHorizontalPadding[] = {3, 6, 6};
   const int kLocationBarVerticalPadding[] = {2, 2, 2};
   const int kNewTabButtonWidth[] = {34, 34, 34};
   const int kOmniboxDropdownBorderInterior[] = {6, 0, 0};
   const int kOmniboxFontPixelSize[] = {16, 14, 14};
   const int kTabCloseButtonTrailingPaddingOverlap[] = {2, 2, 2};
   const int kTabFaviconTitleSpacing[] = {4, 4, 4};
   const int kTabMaximumTitleWidth[] = {175, 175, 175};
   const int kTabPinnedContentWidth[] = {25, 25, 25};
 #if defined(OS_MACOSX)
+  const int kTabTopExclusionHeight[] = {0, 0, 0};
   const int kTabstripNewTabButtonOverlap[] = {8, 8, 8};
   const int kTabstripTabOverlap[] = {19, 19, 19};
 #else
+  const int kTabTopExclusionHeight[] = {2, 2, 2};
   const int kTabstripNewTabButtonOverlap[] = {11, 11, 11};
   const int kTabstripTabOverlap[] = {26, 26, 26};
 #endif
   const int kTabstripToolbarOverlap[] = {3, 3, 3};
   const int kToolbarContentShadowHeight[] = {0, 0, 0};
   const int kToolbarContentShadowHeightAsh[] = {2, 0, 0};
   const int kToolbarElementPadding[] = {0, 0, 8};
   const int kToolbarLocationBarRightPadding[] = {0, 4, 8};
   const int kToolbarStandardSpacing[] = {3, 4, 8};
 
@@ skipping 30 matching lines @@
     case TABSTRIP_TOOLBAR_OVERLAP:
       return kTabstripToolbarOverlap[mode];
     case TAB_CLOSE_BUTTON_TRAILING_PADDING_OVERLAP:
       return kTabCloseButtonTrailingPaddingOverlap[mode];
     case TAB_FAVICON_TITLE_SPACING:
       return kTabFaviconTitleSpacing[mode];
     case TAB_MAXIMUM_TITLE_WIDTH:
       return kTabMaximumTitleWidth[mode];
     case TAB_PINNED_CONTENT_WIDTH:
       return kTabPinnedContentWidth[mode];
+    case TAB_TOP_EXCLUSION_HEIGHT:
+      return kTabTopExclusionHeight[mode];
     case TOOLBAR_CONTENT_SHADOW_HEIGHT:
       return kToolbarContentShadowHeight[mode];
     case TOOLBAR_CONTENT_SHADOW_HEIGHT_ASH:
       return kToolbarContentShadowHeightAsh[mode];
     case TOOLBAR_ELEMENT_PADDING:
       return kToolbarElementPadding[mode];
     case TOOLBAR_LOCATION_BAR_RIGHT_PADDING:
       return kToolbarLocationBarRightPadding[mode];
     case TOOLBAR_STANDARD_SPACING:
       return kToolbarStandardSpacing[mode];
@@ skipping 45 matching lines @@
                          kToolbarBottomPadding[mode],
                          kToolbarRightPadding[mode]);
     case TOOLBAR_BUTTON: {
       const int inset = kToolbarButtonPadding[mode];
       return gfx::Insets(inset, inset, inset, inset);
     }
   }
   NOTREACHED();
   return gfx::Insets();
 }