Merge 259353 "Mark drags starting in web content as tainted to a..."

content/browser/web_contents/web_drag_source_gtk.cc

Index: content/browser/web_contents/web_drag_source_gtk.cc
===================================================================
--- content/browser/web_contents/web_drag_source_gtk.cc	(revision 259999)
+++ content/browser/web_contents/web_drag_source_gtk.cc	(working copy)
@@ -79,7 +79,7 @@
     return false;
   }
 
-  int targets_mask = 0;
+  int targets_mask = ui::RENDERER_TAINT;
 
   if (!drop_data.text.string().empty())
     targets_mask |= ui::TEXT_PLAIN;
@@ -285,6 +285,17 @@
       break;
     }
 
+    case ui::RENDERER_TAINT: {
+      static const char kPlaceholder[] = "x";
+      gtk_selection_data_set(
+          selection_data,
+          ui::GetAtomForTarget(ui::RENDERER_TAINT),
+          kBitsPerByte,
+          reinterpret_cast<const guchar*>(kPlaceholder),
+          strlen(kPlaceholder));
+      break;
+    }
+
     default:
       NOTREACHED();
   }