Fix window zoom in a sane way, remove nasty casts.

chrome/browser/ui/cocoa/browser_window_controller.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
 
 #include <cmath>
 #include <numeric>
 
 #include "base/command_line.h"
@@ skipping 678 matching lines @@
   // (bounded by available width).
   const CGFloat kProportion = 0.6;
   CGFloat zoomedWidth =
       std::max(kProportion * frame.size.width,
                std::min(kProportion * frame.size.height, frame.size.width));
 
   WebContents* contents = browser_->GetSelectedWebContents();
   if (contents) {
     // If the intrinsic width is bigger, then make it the zoomed width.
     const int kScrollbarWidth = 16;  // TODO(viettrungluu): ugh.
-    TabContentsViewMac* tab_contents_view =
-        static_cast<TabContentsViewMac*>(contents->GetView());
     CGFloat intrinsicWidth = static_cast<CGFloat>(
-        tab_contents_view->preferred_width() + kScrollbarWidth);
+        contents->GetPreferredSize().width() + kScrollbarWidth);
     zoomedWidth = std::max(zoomedWidth,
                            std::min(intrinsicWidth, frame.size.width));
   }
 
   // Never shrink from the current size on zoom (see above).
   NSRect currentFrame = [[self window] frame];
   zoomedWidth = std::max(zoomedWidth, currentFrame.size.width);
 
   // |frame| determines our maximum extents. We need to set the origin of the
   // frame -- and only move it left if necessary.
@@ skipping 1455 matching lines @@
 
 - (BOOL)supportsBookmarkBar {
   return [self supportsWindowFeature:Browser::FEATURE_BOOKMARKBAR];
 }
 
 - (BOOL)isTabbedWindow {
   return browser_->is_type_tabbed();
 }
 
 @end  // @implementation BrowserWindowController(WindowType)