Instant: Use only one hidden WebContents per profile.

chrome/browser/ui/cocoa/tab_contents/instant_preview_controller_mac.mm

-// Copyright 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.
-
-#include "chrome/browser/ui/cocoa/tab_contents/instant_preview_controller_mac.h"
-
-#include "chrome/browser/instant/instant_model.h"
-#include "chrome/browser/ui/browser.h"
-#import "chrome/browser/ui/cocoa/browser_window_controller.h"
-#import "chrome/browser/ui/cocoa/tab_contents/previewable_contents_controller.h"
-
-InstantPreviewControllerMac::InstantPreviewControllerMac(
-    Browser* browser,
-    BrowserWindowController* window,
-    PreviewableContentsController* preview)
-    : InstantPreviewController(browser),
-      window_(window),
-      preview_(preview) {
-}
-
-InstantPreviewControllerMac::~InstantPreviewControllerMac() {
-}
-
-void InstantPreviewControllerMac::PreviewStateChanged(
-    const InstantModel& model) {
-  if (model.mode().is_ntp() || model.mode().is_search_suggestions()) {
-    // Drop shadow is only needed if search mode is not |NTP| and preview does
-    // not fill up the entire contents page.
-    BOOL drawDropShadow = !model.mode().is_ntp() &&
-        !(model.height() == 100 &&
-          model.height_units() == INSTANT_SIZE_PERCENT);
-    [preview_ setPreview:model.GetPreviewContents()
-                  height:model.height()
-             heightUnits:model.height_units()
-          drawDropShadow:drawDropShadow];
-  } else {
-    [preview_ setPreview:NULL
-                  height:0
-             heightUnits:INSTANT_SIZE_PIXELS
-          drawDropShadow:NO];
-  }
-  browser_->MaybeUpdateBookmarkBarStateForInstantPreview(model.mode());
-  [window_ updateBookmarkBarStateForInstantPreview];
-}