Made sync code build and pass unit tests on OS X.

chrome/browser/tab_contents/tab_contents_view_mac.mm

 // Copyright (c) 2006-2008 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 <Carbon/Carbon.h>
 
 #include "chrome/browser/tab_contents/tab_contents_view_mac.h"
 
 #include <string>
 
 #include "chrome/browser/browser.h" // TODO(beng): this dependency is awful.
 #import "chrome/browser/cocoa/focus_tracker.h"
 #import "chrome/browser/cocoa/chrome_browser_window.h"
 #import "chrome/browser/cocoa/browser_window_controller.h"
 #include "chrome/browser/global_keyboard_shortcuts_mac.h"
 #include "chrome/browser/cocoa/sad_tab_view.h"
 #import "chrome/browser/cocoa/web_drag_source.h"
 #import "chrome/browser/cocoa/web_drop_target.h"
+#include "chrome/browser/renderer_host/render_view_host_factory.h"
 #include "chrome/browser/renderer_host/render_widget_host.h"
 #include "chrome/browser/renderer_host/render_widget_host_view_mac.h"
 #include "chrome/browser/tab_contents/render_view_context_menu_mac.h"
 #include "chrome/browser/tab_contents/tab_contents.h"
 #include "chrome/common/notification_type.h"
 #include "chrome/common/notification_service.h"
 #include "chrome/common/render_messages.h"
 #import "third_party/mozilla/include/NSPasteboard+Utils.h"
 
 #include "chrome/common/temp_scaffolding_stubs.h"
@@ skipping 35 matching lines @@
 }
 
 void TabContentsViewMac::CreateView(const gfx::Size& initial_size) {
   TabContentsViewCocoa* view =
       [[TabContentsViewCocoa alloc] initWithTabContentsViewMac:this];
   cocoa_view_.reset(view);
 }
 
 RenderWidgetHostView* TabContentsViewMac::CreateViewForWidget(
     RenderWidgetHost* render_widget_host) {
-  DCHECK(!render_widget_host->view());
+  if (render_widget_host->view()) {
+    // During testing, the view will already be set up in most cases to the
+    // test view, so we don't want to clobber it with a real one. To verify that
+    // this actually is happening (and somebody isn't accidentally creating the
+    // view twice), we check for the RVH Factory, which will be set when we're
+    // making special ones (which go along with the special views).
+    DCHECK(RenderViewHostFactory::has_factory());
+    return render_widget_host->view();
+  }
+
   RenderWidgetHostViewMac* view =
       new RenderWidgetHostViewMac(render_widget_host);
 
   // Fancy layout comes later; for now just make it our size and resize it
   // with us. In case there are other siblings of the content area, we want
   // to make sure the content area is on the bottom so other things draw over
   // it.
   NSView* view_view = view->native_view();
   [view_view setFrame:[cocoa_view_.get() bounds]];
   [view_view setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
@@ skipping 369 matching lines @@
 }
 
 - (BOOL)performDragOperation:(id<NSDraggingInfo>)sender {
   return [dropTarget_ performDragOperation:sender view:self];
 }
 
 // Tons of stuff goes here, where we grab events going on in Cocoaland and send
 // them into the C++ system. TODO(avi): all that jazz
 
 @end