Route OnDragEvent through ViewAndroid tree

ui/android/java/src/org/chromium/ui/base/EventForwarder.java

 // 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.
 
 package org.chromium.ui.base;
 
 import android.annotation.TargetApi;
+import android.content.ClipData;
+import android.content.ClipDescription;
 import android.os.Build;
+import android.view.DragEvent;
 import android.view.MotionEvent;
+import android.view.View;
 
 import org.chromium.base.TraceEvent;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 
 /**
  * Class used to forward view, input events down to native.
  */
 @JNINamespace("ui")
 public class EventForwarder {
     private long mNativeEventForwarder;
 
+    private final boolean mIsDragDropEnabled;

[boliu, 2017/05/24 22:54:02]

nit: final above non-final member variables

[Jinsuk Kim, 2017/05/25 03:18:18]

Done.

+
     // Offsets for the events that passes through.
     private float mCurrentTouchOffsetX;
     private float mCurrentTouchOffsetY;
 
     private int mLastMouseButtonState;
 
     @CalledByNative
-    private static EventForwarder create(long nativeEventForwarder) {
-        return new EventForwarder(nativeEventForwarder);
+    private static EventForwarder create(long nativeEventForwarder, boolean isDragDropEnabled) {
+        return new EventForwarder(nativeEventForwarder, isDragDropEnabled);
     }
 
-    private EventForwarder(long nativeEventForwarder) {
+    private EventForwarder(long nativeEventForwarder, boolean isDragDropEnabled) {
         mNativeEventForwarder = nativeEventForwarder;
+        mIsDragDropEnabled = isDragDropEnabled;
     }
 
     @CalledByNative
     private void destroy() {
         mNativeEventForwarder = 0;
     }
 
     /**
      * @see View#onTouchEvent(MotionEvent)
      */
@@ skipping 171 matching lines @@
         return 0;
     }
 
     public boolean onMouseWheelEvent(
             long timeMs, float x, float y, float ticksX, float ticksY, float pixelsPerTick) {
         assert mNativeEventForwarder != 0;
         nativeOnMouseWheelEvent(mNativeEventForwarder, timeMs, x, y, ticksX, ticksY, pixelsPerTick);
         return true;
     }
 
+    /**
+     * @see View#onDragEvent(DragEvent)
+     * @param event {@link DragEvent} instance.
+     * @param containerView A view on which the drag event is taking place.
+     */
+    @TargetApi(Build.VERSION_CODES.N)
+    public boolean onDragEvent(DragEvent event, View containerView) {
+        if (mNativeEventForwarder == 0 || Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
+            return false;
+        }
+
+        ClipDescription clipDescription = event.getClipDescription();
+
+        // text/* will match text/uri-list, text/html, text/plain.
+        String[] mimeTypes =
+                clipDescription == null ? new String[0] : clipDescription.filterMimeTypes("text/*");
+
+        if (event.getAction() == DragEvent.ACTION_DRAG_STARTED) {
+            // TODO(hush): support dragging more than just text.
+            return mimeTypes != null && mimeTypes.length > 0 && mIsDragDropEnabled;
+        }
+
+        StringBuilder content = new StringBuilder("");
+        if (event.getAction() == DragEvent.ACTION_DROP) {
+            // TODO(hush): obtain dragdrop permissions, when dragging files into Chrome/WebView is
+            // supported. Not necessary to do so for now, because only text dragging is supported.
+            ClipData clipData = event.getClipData();
+            final int itemCount = clipData.getItemCount();
+            for (int i = 0; i < itemCount; i++) {
+                ClipData.Item item = clipData.getItemAt(i);
+                content.append(item.coerceToStyledText(containerView.getContext()));
+            }
+        }
+
+        int[] locationOnScreen = new int[2];
+        containerView.getLocationOnScreen(locationOnScreen);
+
+        // All coordinates are in device pixel. Conversion to DIP happens in the native.
+        int x = (int) (event.getX() + mCurrentTouchOffsetX);
+        int y = (int) (event.getY() + mCurrentTouchOffsetY);
+        int screenX = x + locationOnScreen[0];
+        int screenY = y + locationOnScreen[1];
+
+        nativeOnDragEvent(mNativeEventForwarder, event.getAction(), x, y, screenX, screenY,
+                mimeTypes, content.toString());
+        return true;
+    }
+
     // All touch events (including flings, scrolls etc) accept coordinates in physical pixels.
     private native boolean nativeOnTouchEvent(long nativeEventForwarder, MotionEvent event,
             long timeMs, int action, int pointerCount, int historySize, int actionIndex, float x0,
             float y0, float x1, float y1, int pointerId0, int pointerId1, float touchMajor0,
             float touchMajor1, float touchMinor0, float touchMinor1, float orientation0,
             float orientation1, float tilt0, float tilt1, float rawX, float rawY,
             int androidToolType0, int androidToolType1, int androidButtonState,
             int androidMetaState, boolean isTouchHandleEvent);
     private native void nativeOnMouseEvent(long nativeEventForwarder, long timeMs, int action,
             float x, float y, int pointerId, float pressure, float orientation, float tilt,
             int changedButton, int buttonState, int metaState, int toolType);
     private native void nativeOnMouseWheelEvent(long nativeEventForwarder, long timeMs, float x,
             float y, float ticksX, float ticksY, float pixelsPerTick);
+    private native void nativeOnDragEvent(long nativeEventForwarder, int action, int x, int y,
+            int screenX, int screenY, String[] mimeTypes, String content);
 }