Disable WebView/Chrome's drag and drop feature on M and below.

content/browser/web_contents/web_contents_view_android.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/web_contents/web_contents_view_android.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/logging.h"
 #include "content/browser/android/content_view_core_impl.h"
@@ skipping 233 matching lines @@
   if (!native_view) {
     // Need to clear drag and drop state in blink.
     OnDragEnded();
     return;
   }
 
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jstring> jtext =
       ConvertUTF16ToJavaString(env, drop_data.text.string());
 
-  native_view->StartDragAndDrop(jtext,
-                                gfx::ConvertToJavaBitmap(image.bitmap()));
+  if (!native_view->StartDragAndDrop(
+          jtext, gfx::ConvertToJavaBitmap(image.bitmap()))) {
+    // Need to clear drag and drop state in blink.
+    OnDragEnded();
+    return;
+  }
 
   if (content_view_core_)
     content_view_core_->HidePopupsAndPreserveSelection();
 }
 
 void WebContentsViewAndroid::UpdateDragCursor(blink::WebDragOperation op) {
   // Intentional no-op because Android does not have cursor.
 }
 
 void WebContentsViewAndroid::OnDragEntered(
@@ skipping 40 matching lines @@
 // This is called when we the renderer asks us to take focus back (i.e., it has
 // iterated past the last focusable element on the page).
 void WebContentsViewAndroid::TakeFocus(bool reverse) {
   if (web_contents_->GetDelegate() &&
       web_contents_->GetDelegate()->TakeFocus(web_contents_, reverse))
     return;
   web_contents_->GetRenderWidgetHostView()->Focus();
 }
 
 } // namespace content