Provide the custom thumbnail for live preview of stacked panels

chrome/browser/ui/views/panels/panel_view.cc

 // Copyright (c) 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/views/panels/panel_view.h"
 
 #include <map>
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/utf_string_conversions.h"
@@ skipping 586 matching lines @@
   GetFrameView()->SetWindowCornerStyle(corner_style);
 }
 
 void PanelView::PanelExpansionStateChanging(Panel::ExpansionState old_state,
                                             Panel::ExpansionState new_state) {
 #if defined(OS_WIN)
   // Live preview is only available since Windows 7.
   if (base::win::GetVersion() < base::win::VERSION_WIN7)
     return;
 
+  if (panel_->collection()->type() != PanelCollection::DOCKED)
+    return;
+
   bool is_minimized = old_state != Panel::EXPANDED;
   bool will_be_minimized = new_state != Panel::EXPANDED;
   if (is_minimized == will_be_minimized)
     return;
 
   HWND native_window = views::HWNDForWidget(window_);
 
   if (!thumbnailer_.get()) {
     DCHECK(native_window);
-    thumbnailer_.reset(new TaskbarWindowThumbnailerWin(native_window));
-    ui::HWNDSubclass::AddFilterToTarget(native_window, thumbnailer_.get());
+    thumbnailer_.reset(new TaskbarWindowThumbnailerWin(native_window, NULL));
   }
 
   // Cache the image at this point.
   if (will_be_minimized) {
     // If the panel is still active (we will deactivate the minimizd panel at
     // later time), we need to paint it immediately as inactive so that we can
     // take a snapshot of inactive panel.
     if (focused_) {
       force_to_paint_as_inactive_ = true;
       ::RedrawWindow(native_window, NULL, NULL,
                      RDW_NOCHILDREN | RDW_INVALIDATE | RDW_UPDATENOW);
     }
 
-    std::vector<HWND> snapshot_hwnds;
-    thumbnailer_->Start(snapshot_hwnds);
+    // Start the thumbnailer and capture the snapshot now.
+    thumbnailer_->Start();
+    thumbnailer_->CaptureSnapshot();
   } else {
     force_to_paint_as_inactive_ = false;
     thumbnailer_->Stop();
   }
 
 #endif
 }
 
 gfx::Size PanelView::WindowSizeFromContentSize(
     const gfx::Size& content_size) const {
@@ skipping 468 matching lines @@
   DCHECK(thickness_for_mouse_resizing > 0);
   SkRegion* region = new SkRegion;
   region->op(0, 0, thickness_for_mouse_resizing, height, SkRegion::kUnion_Op);
   region->op(width - thickness_for_mouse_resizing, 0, width, height,
       SkRegion::kUnion_Op);
   region->op(0, height - thickness_for_mouse_resizing, width, height,
       SkRegion::kUnion_Op);
   web_contents->GetRenderViewHost()->GetView()->SetClickthroughRegion(region);
 #endif
 }