Switch SupportsUserData uses to use unique_ptr.

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

Index: chrome/browser/task_manager/providers/web_contents/web_contents_tag.h
diff --git a/chrome/browser/task_manager/providers/web_contents/web_contents_tag.h b/chrome/browser/task_manager/providers/web_contents/web_contents_tag.h
index 713c201df682fd0165efae82eb1fc3b44b8f7e3d..eff58d04d4a79fd78afca6af7b5ddf5149077895 100644
--- a/chrome/browser/task_manager/providers/web_contents/web_contents_tag.h
+++ b/chrome/browser/task_manager/providers/web_contents/web_contents_tag.h
@@ -25,6 +25,8 @@ class RendererTask;
 // |task_manager::WebContentsTags|.
 class WebContentsTag : public base::SupportsUserData::Data {
  public:
+  ~WebContentsTag() override;
+
   // Retrieves the instance of the WebContentsTag that was attached to the
   // specified WebContents and returns it. If no instance was attached, returns
   // nullptr.
@@ -45,7 +47,6 @@ class WebContentsTag : public base::SupportsUserData::Data {
   friend class WebContentsTags;
 
   explicit WebContentsTag(content::WebContents* contents);
-  ~WebContentsTag() override;
 
  private:
   // The user data key.