Support dragging texts into Android WebView.

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index 89414b4ab13612e3db29577d84c7e4f425d16c15..d468d59bb3e86f6094c85691259e787a1bf2cbc0 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -9,6 +9,7 @@ import android.annotation.TargetApi;
 import android.app.Activity;
 import android.app.SearchManager;
 import android.app.assist.AssistStructure.ViewNode;
+import android.content.ClipData;
 import android.content.ClipboardManager;
 import android.content.ContentResolver;
 import android.content.Context;
@@ -27,6 +28,7 @@ import android.text.TextUtils;
 import android.util.Pair;
 import android.util.TypedValue;
 import android.view.ActionMode;
+import android.view.DragEvent;
 import android.view.HapticFeedbackConstants;
 import android.view.InputDevice;
 import android.view.KeyEvent;
@@ -3110,6 +3112,77 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
     }
 
     /**
+     * Returns the location of the DragEvent normalized by dpi scale. The first 2 points are x and y
+     * coordinates in application window space, the latter 2 points are x and y coordinates in
+     * physical screen space.
+     */
+    private int[] getDragEventLocations(DragEvent event) {
+        int[] locations = new int[4];
+        float scale = (float) DeviceDisplayInfo.create(mContainerView.getContext()).getDIPScale();
+        int[] locationOnScreen = new int[2];
+        mContainerView.getLocationOnScreen(locationOnScreen);
+        float screenX = event.getX() + locationOnScreen[0];
+        float screenY = event.getY() + locationOnScreen[1];
+
+        locations[0] = (int) (event.getX() / scale);
+        locations[1] = (int) (event.getY() / scale);
+        locations[2] = (int) (screenX / scale);
+        locations[3] = (int) (screenY / scale);
+
+        return locations;
+    }
+
+    public void onDragEntered(DragEvent event) {
+        if (mNativeContentViewCore == 0) {
+            return;
+        }
+
+        int[] locations = getDragEventLocations(event);
+        nativeOnDragEntered(
+                mNativeContentViewCore, locations[0], locations[1], locations[2], locations[3]);
+    }
+
+    public void onDragUpdated(DragEvent event) {
+        if (mNativeContentViewCore == 0) {
+            return;
+        }
+
+        int[] locations = getDragEventLocations(event);
+        nativeOnDragUpdated(
+                mNativeContentViewCore, locations[0], locations[1], locations[2], locations[3]);
+    }
+
+    public void onPerformDrop(DragEvent event) {
+        if (mNativeContentViewCore == 0) {
+            return;
+        }
+
+        StringBuilder content = new StringBuilder("");
+
+        // TODO(hush): obtain dragdrop persmissions via reflection, 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(mContainerView.getContext()));
+        }
+
+        int[] locations = getDragEventLocations(event);
+        nativeOnPerformDrop(mNativeContentViewCore, locations[0], locations[1], locations[2],
+                locations[3], content.toString());
+    }
+
+    public void onDragExited() {
+        if (mNativeContentViewCore == 0) {
+            return;
+        }
+
+        nativeOnDragExited(mNativeContentViewCore);
+    }
+
+    /**
      * Offer a long press gesture to the embedding View, primarily for WebView compatibility.
      *
      * @return true if the embedder handled the event.
@@ -3316,4 +3389,11 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
             int x, int y, int w, int h);
 
     private native void nativeSetBackgroundOpaque(long nativeContentViewCoreImpl, boolean opaque);
+    private native void nativeOnDragEntered(
+            long nativeContentViewCoreImpl, int x, int y, int screenX, int screenY);
+    private native void nativeOnDragUpdated(
+            long nativeContentViewCoreImpl, int x, int y, int screenX, int screenY);
+    private native void nativeOnPerformDrop(
+            long nativeContentViewCoreImpl, int x, int y, int screenX, int screenY, String content);
+    private native void nativeOnDragExited(long nativeContentViewCoreImpl);
 }