Support dragging texts into Android WebView.

content/browser/android/content_view_core_impl.cc

Index: content/browser/android/content_view_core_impl.cc
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index 7d636b6f9cd372551f017f41d54572848b612c65..4a6de961608f14836666b5085925a29da4fb4028 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -14,6 +14,7 @@
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/metrics/histogram.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "cc/layers/layer.h"
@@ -55,6 +56,7 @@
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/android/view_android.h"
 #include "ui/android/window_android.h"
+#include "ui/base/clipboard/clipboard.h"
 #include "ui/events/android/motion_event_android.h"
 #include "ui/events/blink/blink_event_util.h"
 #include "ui/events/event_utils.h"
@@ -91,6 +93,17 @@ enum PopupItemType {
   POPUP_ITEM_TYPE_ENABLED,
 };
 
+// A copy of possible DragEvent.getActions().
+// https://developer.android.com/reference/android/view/DragEvent.html
+enum DragEventActions {
+  ACTION_DRAG_STARTED = 1,

[Ted C, 2016/06/30 00:15:42]

any reason we don't generate these the same way we do MotionEvent jni bindings?

from content/public/android/BUILD.gn

generate_jar_jni("jar_jni") {
  jni_package = "content"
  classes = [
    "java/util/HashSet.class",
    "android/view/MotionEvent.class",
  ]
}

Seems like we could add DragEvent here as well.

[hush (inactive), 2016/06/30 18:19:06]

Didn't know we could do that.
Done

+  ACTION_DRAG_LOCATION,
+  ACTION_DROP,
+  ACTION_DRAG_ENDED,
+  ACTION_DRAG_ENTERED,
+  ACTION_DRAG_EXITED,
+};
+
 const void* const kContentViewUserDataKey = &kContentViewUserDataKey;
 
 int GetRenderProcessIdFromRenderViewHost(RenderViewHost* host) {
@@ -1473,6 +1486,64 @@ void ContentViewCoreImpl::SetBackgroundOpaque(JNIEnv* env,
   }
 }
 
+void ContentViewCoreImpl::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) {
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+
+  const gfx::Point location(x, y);
+  const gfx::Point screen_location(screen_x, screen_y);
+
+  std::vector<base::string16> mime_types;
+  base::android::AppendJavaStringArrayToStringVector(env, j_mimeTypes,
+                                                     &mime_types);
+  switch (action) {
+    case ACTION_DRAG_ENTERED: {
+      std::vector<DropData::Metadata> metadata;
+      for (const base::string16& mime_type : mime_types) {
+        metadata.push_back(DropData::Metadata::CreateForMimeType(
+            DropData::Kind::STRING, mime_type));
+      }
+      wcva->OnDragEntered(metadata, location, screen_location);
+      break;
+    }
+    case ACTION_DRAG_LOCATION: {
+      wcva->OnDragUpdated(location, screen_location);
+      break;
+    }
+    case ACTION_DROP: {
+      base::string16 text_to_drop = ConvertJavaStringToUTF16(env, j_content);
+      DropData drop_data;
+      drop_data.did_originate_from_renderer = false;
+      for (const base::string16& mime_type : mime_types) {
+        if (base::EqualsASCII(mime_type, ui::Clipboard::kMimeTypeURIList)) {
+          drop_data.url = GURL(text_to_drop);
+        } else if (base::EqualsASCII(mime_type, ui::Clipboard::kMimeTypeText)) {
+          drop_data.text = base::NullableString16(text_to_drop, false);
+        } else {
+          drop_data.html = base::NullableString16(text_to_drop, false);
+        }
+      }
+
+      wcva->OnPerformDrop(&drop_data, location, screen_location);
+      break;
+    }
+    case ACTION_DRAG_EXITED:
+      wcva->OnDragExited();
+      break;
+    default:  // STARTED and ENDED. Nothing meaningful to do.
+      break;
+  }
+}
+
 void ContentViewCoreImpl::RequestTextSurroundingSelection(
     int max_length,
     const base::Callback<