dragend fix for mac <webview>.

content/browser/browser_plugin/browser_plugin_embedder.h

Index: content/browser/browser_plugin/browser_plugin_embedder.h
diff --git a/content/browser/browser_plugin/browser_plugin_embedder.h b/content/browser/browser_plugin/browser_plugin_embedder.h
index a173fec74fa36e6f0dea05fd1be8338e924e68f3..9216cd2c3d3a34848085f37569543431ad4d1730 100644
--- a/content/browser/browser_plugin/browser_plugin_embedder.h
+++ b/content/browser/browser_plugin/browser_plugin_embedder.h
@@ -75,6 +75,8 @@ class CONTENT_EXPORT BrowserPluginEmbedder : public WebContentsObserver {
 
   BrowserPluginGuestManager* GetBrowserPluginGuestManager() const;
 
+  void ClearGuestDragStateIfApplicable();
+
   bool DidSendScreenRectsCallback(WebContents* guest_web_contents);
 
   bool SetZoomLevelCallback(double level, WebContents* guest_web_contents);
@@ -108,6 +110,10 @@ class CONTENT_EXPORT BrowserPluginEmbedder : public WebContentsObserver {
   // status messages to the correct guest.
   base::WeakPtr<BrowserPluginGuest> guest_started_drag_;
 
+  // Keeps track of "dragend" state.
+  bool seen_system_drag_ended_;
+  bool seen_drag_source_ended_at_;
+
   base::WeakPtrFactory<BrowserPluginEmbedder> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserPluginEmbedder);