Switch SupportsUserData uses to use unique_ptr.

chrome/browser/task_manager/providers/web_contents/printing_tag.h

Index: chrome/browser/task_manager/providers/web_contents/printing_tag.h
diff --git a/chrome/browser/task_manager/providers/web_contents/printing_tag.h b/chrome/browser/task_manager/providers/web_contents/printing_tag.h
index dfcd671340cf43d5b422b869a3d9ad75d34aa2f9..0d113dbaa43c6b8909e852c1e765ca9de0958327 100644
--- a/chrome/browser/task_manager/providers/web_contents/printing_tag.h
+++ b/chrome/browser/task_manager/providers/web_contents/printing_tag.h
@@ -15,6 +15,8 @@ namespace task_manager {
 // and background printing.
 class PrintingTag : public WebContentsTag {
  public:
+  ~PrintingTag() override;
+
   // task_manager::WebContentsTag:
   PrintingTask* CreateTask() const override;
 
@@ -22,7 +24,6 @@ class PrintingTag : public WebContentsTag {
   friend class WebContentsTags;
 
   explicit PrintingTag(content::WebContents* web_contents);
-  ~PrintingTag() override;
 
   DISALLOW_COPY_AND_ASSIGN(PrintingTag);
 };