Instant: Use only one hidden WebContents per profile.

chrome/browser/ui/cocoa/tab_contents/instant_overlay_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_overlay_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/overlayable_contents_controller.h"
+
+InstantOverlayControllerMac::InstantOverlayControllerMac(
+    Browser* browser,
+    BrowserWindowController* window,
+    OverlayableContentsController* overlay)
+    : InstantOverlayController(browser),
+      window_(window),
+      overlay_(overlay) {
+}
+
+InstantOverlayControllerMac::~InstantOverlayControllerMac() {
+}
+
+void InstantOverlayControllerMac::OverlayStateChanged(
+    const InstantModel& model) {
+  if (model.overlay()) {
+    // Drop shadow is only needed if the overlay does not fill up the entire
+    // contents page. TODO(sail): Use the computed height, a la the Views code.
+    BOOL drawDropShadow = model.height() != 100 || model.is_height_in_pixels();
+    [overlay_ setOverlay:model.overlay()
+                  height:model.height()
+        isHeightInPixels:model.is_height_in_pixels()
+          drawDropShadow:drawDropShadow];
+    browser_->MaybeUpdateBookmarkBarStateForInstantOverlay();
+  } else {
+    [overlay_ setOverlay:NULL
+                  height:0
+        isHeightInPixels:NO
+          drawDropShadow:NO];
+  }
+  [window_ updateBookmarkBarStateForInstantOverlay];
+}