Reset overscroll state when OverscrollWindowDelegate is destroyed.

content/browser/web_contents/aura/overscroll_window_delegate.h

Index: content/browser/web_contents/aura/overscroll_window_delegate.h
diff --git a/content/browser/web_contents/aura/overscroll_window_delegate.h b/content/browser/web_contents/aura/overscroll_window_delegate.h
index 251daac83fccca7a21e785d38648e1b445b06f67..a41adb05765f1322ed160dd904747833c116f13f 100644
--- a/content/browser/web_contents/aura/overscroll_window_delegate.h
+++ b/content/browser/web_contents/aura/overscroll_window_delegate.h
@@ -50,13 +50,13 @@ class CONTENT_EXPORT OverscrollWindowDelegate
   OverscrollControllerDelegate* delegate_;
 
   // The current overscroll mode.
-  OverscrollMode overscroll_mode_;
+  OverscrollMode overscroll_mode_ = OVERSCROLL_NONE;
 
   // The current overscroll source.
-  OverscrollSource overscroll_source_;
+  OverscrollSource overscroll_source_ = OverscrollSource::NONE;
 
   // The latest delta_x scroll update.
-  float delta_x_;
+  float delta_x_ = 0.f;
 
   // The ratio of overscroll at which we consider the overscroll completed.
   const float complete_threshold_ratio_;
@@ -68,7 +68,7 @@ class CONTENT_EXPORT OverscrollWindowDelegate
 
   // The threshold for starting the overscroll gesture for the current touch
   // input.
-  float active_start_threshold_;
+  float active_start_threshold_ = 0.f;
 
   DISALLOW_COPY_AND_ASSIGN(OverscrollWindowDelegate);
 };