Add Linux support for getting the thumbnail and wire into the switcher.

chrome/browser/gtk/tabs/dragged_tab_gtk.cc

 // Copyright (c) 2009 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/gtk/tabs/dragged_tab_gtk.h"
 
 #include <gdk/gdk.h>
 
 #include "app/gfx/canvas_paint.h"
 #include "base/gfx/gtk_util.h"
@@ skipping 269 matching lines @@
   gfx::Canvas canvas(ps.width(), ps.height(), false);
   canvas.drawRect(rc, paint);
 
   return canvas.ExtractBitmap();
 }
 
 void DraggedTabGtk::PaintScreenshotIntoCanvas(gfx::Canvas* canvas,
                                               const gfx::Rect& target_bounds) {
   gfx::Rect rect(0, 0,
                  contents_->allocation.width, contents_->allocation.height);
-  SkBitmap* bitmap = backing_store_->PaintRectToBitmap(rect);
-  if (bitmap) {
-    canvas->DrawBitmapInt(*bitmap, 0, renderer_->bounds().height());
-    delete bitmap;
-  }
+  SkBitmap bitmap = backing_store_->PaintRectToBitmap(rect);
+  if (!bitmap.isNull())
+    canvas->DrawBitmapInt(bitmap, 0, renderer_->bounds().height());
 }
 
 // static
 gboolean DraggedTabGtk::OnExposeEvent(GtkWidget* widget,
                                       GdkEventExpose* event,
                                       DraggedTabGtk* dragged_tab) {
   SkBitmap bmp;
   if (dragged_tab->attached_) {
     bmp = dragged_tab->PaintAttachedTab();
   } else {
     bmp = dragged_tab->PaintDetachedView();
   }
 
   if (gtk_util::IsScreenComposited()) {
     dragged_tab->SetContainerTransparency();
   } else {
     dragged_tab->SetContainerShapeMask(bmp);
   }
 
   gfx::CanvasPaint canvas(event, false);
   canvas.DrawBitmapInt(bmp, 0, 0);
 
   // We've already drawn the tab, so don't propagate the expose-event signal.
   return TRUE;
 }