Use a font size of 9pt in the tab titles. This is a bit

chrome/browser/gtk/tabs/tab_renderer_gtk.cc

 // Copyright (c) 2009 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/gtk/tabs/tab_renderer_gtk.h"
 
 #include <algorithm>
 
 #include "app/gfx/canvas_paint.h"
 #include "app/gfx/favicon_size.h"
@@ skipping 525 matching lines @@
             rb.GetBitmapNamed(IDR_TAB_CLOSE_MASK));
       }
     }
   } else {
     close_button_bounds_.SetRect(0, 0, 0, 0);
   }
 
   if (!is_pinned() || width() >= kPinnedTabRendererAsTabWidth) {
     // Size the Title text to fill the remaining space.
     int title_left = favicon_bounds_.right() + kFavIconTitleSpacing;
-    // Center the mean line of the text in the content area.
-    int title_top = kTopPadding +
-        (content_height - title_font_->baseline()) / 2;
+    // Center the text in the content area.  We need to shift the text up by a
+    // pixel to match Windows.  TODO(estade): Figure out why we need to shift
+    // the text up by a pixel.  http://crbug.com/18555
+    int title_top = kTopPadding + (content_height - title_font_height_) / 2 - 1;
 
     // If the user has big fonts, the title will appear rendered too far down
     // on the y-axis if we use the regular top padding, so we need to adjust it
     // so that the text appears centered.
     gfx::Size minimum_size = GetMinimumUnselectedSize();
     int text_height = title_top + title_font_height_ + kBottomPadding;
     if (text_height > minimum_size.height())
       title_top -= (text_height - minimum_size.height()) / 2;
 
     int title_width;
@@ skipping 322 matching lines @@
 }
 
 // static
 void TabRendererGtk::InitResources() {
   if (initialized_)
     return;
 
   LoadTabImages();
 
   ResourceBundle& rb = ResourceBundle::GetSharedInstance();
-  // Force the font size to 8pt.
+  // Force the font size to 9pt, which matches Windows' default font size
+  // (taken from the system).
   gfx::Font base_font = rb.GetFont(ResourceBundle::BaseFont);
-  title_font_ = new gfx::Font(gfx::Font::CreateFont(base_font.FontName(), 8));
+  title_font_ = new gfx::Font(gfx::Font::CreateFont(base_font.FontName(), 9));
   title_font_height_ = title_font_->height();
 
   crashed_fav_icon = rb.GetBitmapNamed(IDR_SAD_FAVICON);
 
   initialized_ = true;
 }