Support dragging texts into Android WebView.

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index a710d513896e2f65cc45be90c0a0c6231c552b5f..681844751cb0e2bca6e2de5af54947ad015857e9 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -6,6 +6,7 @@ package org.chromium.android_webview;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
+import android.content.ClipDescription;
 import android.content.ComponentCallbacks2;
 import android.content.Context;
 import android.content.Intent;
@@ -2974,8 +2975,30 @@ public class AwContents implements SmartClipProvider,
 
         @Override
         public boolean onDragEvent(DragEvent event) {
-            // TODO(hush): implement this. crbug.com/584789
-            return false;
+            switch (event.getAction()) {
+                case DragEvent.ACTION_DRAG_STARTED:
+                    ClipDescription clipDescription = event.getClipDescription();
+                    // TODO(hush): support dragging more than just text.
+                    return clipDescription.hasMimeType(ClipDescription.MIMETYPE_TEXT_HTML)
+                            || clipDescription.hasMimeType(clipDescription.MIMETYPE_TEXT_PLAIN);
+                case DragEvent.ACTION_DRAG_ENTERED:
+                    mContentViewCore.onDragEntered(event);
+                    return true;
+                case DragEvent.ACTION_DRAG_LOCATION:
+                    mContentViewCore.onDragUpdated(event);
+                    return true;
+                case DragEvent.ACTION_DROP:
+                    // TODO(hush): onPerformDrop should return false when the receiving object does
+                    // not accept the text drop.
+                    mContentViewCore.onPerformDrop(event);
+                    return true;
+                case DragEvent.ACTION_DRAG_EXITED:
+                    mContentViewCore.onDragExited();
+                    return true;
+                case DragEvent.ACTION_DRAG_ENDED:
+                default:
+                    return true;
+            }
         }
 
         @Override