[Mac] Organize some files into chrome/browser/ui/cocoa/tab_contents/....

chrome/browser/ui/cocoa/previewable_contents_controller.mm

-// Copyright (c) 2010 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/previewable_contents_controller.h"
-
-#include "base/logging.h"
-#include "base/mac/mac_util.h"
-#include "chrome/browser/tab_contents/tab_contents.h"
-
-@implementation PreviewableContentsController
-
-@synthesize activeContainer = activeContainer_;
-
-- (id)init {
-  if ((self = [super initWithNibName:@"PreviewableContents"
-                              bundle:base::mac::MainAppBundle()])) {
-  }
-  return self;
-}
-
-- (void)showPreview:(TabContents*)preview {
-  DCHECK(preview);
-
-  // Remove any old preview contents before showing the new one.
-  if (previewContents_)
-    [previewContents_->GetNativeView() removeFromSuperview];
-
-  previewContents_ = preview;
-  NSView* previewView = previewContents_->GetNativeView();
-  [previewView setFrame:[[self view] bounds]];
-
-  // Hide the active container and add the preview contents.
-  [activeContainer_ setHidden:YES];
-  [[self view] addSubview:previewView];
-}
-
-- (void)hidePreview {
-  DCHECK(previewContents_);
-
-  // Remove the preview contents and reshow the active container.
-  [previewContents_->GetNativeView() removeFromSuperview];
-  [activeContainer_ setHidden:NO];
-
-  previewContents_ = nil;
-}
-
-- (BOOL)isShowingPreview {
-  return previewContents_ != nil;
-}
-
-@end