Route OnDragEvent through ViewAndroid tree

ui/android/event_forwarder.h

 // Copyright 2017 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.
 
 #ifndef UI_ANDROID_EVENT_FORWARDER_H_
 #define UI_ANDROID_EVENT_FORWARDER_H_
 
 #include "base/android/scoped_java_ref.h"
 
 namespace ui {
@@ skipping 52 matching lines @@
 
   void OnMouseWheelEvent(JNIEnv* env,
                          const base::android::JavaParamRef<jobject>& obj,
                          jlong time_ms,
                          jfloat x,
                          jfloat y,
                          jfloat ticks_x,
                          jfloat ticks_y,
                          jfloat pixels_per_tick);
 
+  void OnDragEvent(JNIEnv* env,
+                   const base::android::JavaParamRef<jobject>& jobj,
+                   jint action,
+                   jint x,
+                   jint y,
+                   jint screen_x,
+                   jint screen_y,
+                   const base::android::JavaParamRef<jobjectArray>& j_mimeTypes,
+                   const base::android::JavaParamRef<jstring>& j_content);
+
  private:
   friend class ViewAndroid;
 
   explicit EventForwarder(ViewAndroid* view);
 
   base::android::ScopedJavaLocalRef<jobject> GetJavaObject();
 
   ViewAndroid* const view_;
   base::android::ScopedJavaGlobalRef<jobject> java_obj_;
 
   DISALLOW_COPY_AND_ASSIGN(EventForwarder);
 };
 
 bool RegisterEventForwarder(JNIEnv* env);
 
 }  // namespace ui
 
 #endif  // UI_ANDROID_EVENT_FORWARDER_H_