Provide the custom thumbnail for live preview of stacked panels

chrome/browser/ui/views/panels/taskbar_window_thumbnailer_win.h

Index: chrome/browser/ui/views/panels/taskbar_window_thumbnailer_win.h
diff --git a/chrome/browser/ui/views/panels/taskbar_window_thumbnailer_win.h b/chrome/browser/ui/views/panels/taskbar_window_thumbnailer_win.h
index 909d8b68371f07b1f2336942441da1b09ae42242..a779cd8a467ee39529873208b6eb656330fc034e 100644
--- a/chrome/browser/ui/views/panels/taskbar_window_thumbnailer_win.h
+++ b/chrome/browser/ui/views/panels/taskbar_window_thumbnailer_win.h
@@ -11,17 +11,25 @@
 
 class SkBitmap;
 
+class TaskbarWindowThumbnailerDelegateWin {
+ public:
+  // Returns the handle list of all windows that are used to construct the
+  // thumbnail. If empty list is returned, the snapshot of current window
+  // is used.
+  virtual std::vector<HWND> GetSnapshotWindowHandles() const = 0;
+};
+
 // Provides the custom thumbnail and live preview for the window that appears
 // in the taskbar (Windows 7 and later).
 class TaskbarWindowThumbnailerWin : public ui::HWNDMessageFilter {
  public:
-  explicit TaskbarWindowThumbnailerWin(HWND hwnd);
+  TaskbarWindowThumbnailerWin(HWND hwnd,
+                              TaskbarWindowThumbnailerDelegateWin* delegate);
   virtual ~TaskbarWindowThumbnailerWin();
 
-  // Use the snapshots from all the windows in |snapshot_hwnds| to construct
-  // the thumbnail. If |snapshot_hwnds| is empty, use the snapshot of current
-  // window.
-  void Start(const std::vector<HWND>& snapshot_hwnds);
+  // If |capture_now| is true, the snapshot image is captured immediately.

[Dmitry Titov, 2013/05/29 01:14:48]

capture_now -> should_capture_now
Can we rename it to "capture_first_snapshot_immediately"?

[jianli, 2013/05/29 18:31:52]

Renamed to capture_snapshot_immediately.

+  // Otherwise, it will be captured only when the system requests it.
+  void Start(bool should_capture_now);
   void Stop();
 
  private:
@@ -33,8 +41,7 @@ class TaskbarWindowThumbnailerWin : public ui::HWNDMessageFilter {
                              LRESULT* l_result) OVERRIDE;
 
   // Message handlers.
-  bool OnDwmSendIconicThumbnail(
-      int width, int height, LRESULT* l_result);
+  bool OnDwmSendIconicThumbnail(int width, int height, LRESULT* l_result);
   bool OnDwmSendIconicLivePreviewBitmap(LRESULT* l_result);
 
   // Captures and returns the screenshot of the window. The caller is
@@ -42,7 +49,7 @@ class TaskbarWindowThumbnailerWin : public ui::HWNDMessageFilter {
   SkBitmap* CaptureWindowImage() const;
 
   HWND hwnd_;
-  std::vector<HWND> snapshot_hwnds_;
+  TaskbarWindowThumbnailerDelegateWin* delegate_;

[Dmitry Titov, 2013/05/29 01:14:48]

Please add a comment on Weak or not, who owns, why this pointer is always valid
during lifetime of the thumbnailer.

[jianli, 2013/05/29 18:31:52]

Done.

   scoped_ptr<SkBitmap> capture_bitmap_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskbarWindowThumbnailerWin);