Implement Instant on Mac

chrome/browser/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/cocoa/previewable_contents_controller.h"
 
 #include "base/logging.h"
 #include "base/mac_util.h"
 #include "chrome/browser/tab_contents/tab_contents.h"
 
 @interface PreviewableContentsController(PrivateMethods)
 // Shows or hides the "close preview" button.  Adds the button to the view
 // hierarchy, if needed.
 - (void)showCloseButton:(BOOL)show;
 @end
 
 @implementation PreviewableContentsController
 
 @synthesize activeContainer = activeContainer_;
 
 - (id)init {
   if ((self = [super initWithNibName:@"PreviewableContents"
                               bundle:mac_util::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, add the preview contents, and show the tear
   // image.
   [activeContainer_ setHidden:YES];
   [[self view] addSubview:previewView];
   [self showCloseButton:YES];
 }
 
@@ skipping 34 matching lines @@
   // Add the close button to the upper left corner.
   NSView* view = [self view];
   NSRect frame = [closeButton_ frame];
   frame.origin.x = NSMinX([view bounds]);
   frame.origin.y = NSMaxY([view bounds]) - NSHeight(frame);
   [closeButton_ setFrame:frame];
   [view addSubview:closeButton_];
 }
 
 @end