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..e46b94bd704de2862152e5e80bea5b60b4a48cdf 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 +93,15 @@ enum PopupItemType {
   POPUP_ITEM_TYPE_ENABLED,
 };
 
+enum DragEventActions {
+  ACTION_DRAG_STARTED = 1,

[dcheng, 2016/06/24 23:07:53]

Nit: enum class, and just call the members STARTED, etc (it's also not clear
what DRAG_LOCATION means, maybe call it MOVED or UPDATED or something?)

[hush (inactive), 2016/06/27 19:01:54]

Sorry I can't use enum clas here. They have to be ints. This enum is the mirror
list of actions of DragEvent in android. I will put a comment here. And that's
also why these events are defined in this order and STARTED = 1.
https://developer.android.com/reference/android/view/DragEvent.html

+  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 +1484,61 @@ void ContentViewCoreImpl::SetBackgroundOpaque(JNIEnv* env,
   }
 }
 
+void ContentViewCoreImpl::OnDragEvent(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj,
+    int action,
+    const JavaParamRef<jintArray>& j_locations,
+    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());
+
+  std::vector<int> locations;
+  base::android::JavaIntArrayToIntVector(env, j_locations, &locations);
+
+  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 (base::string16 mime_type : mime_types) {
+        metadata.push_back(DropData::Metadata::CreateForMimeType(
+            DropData::Kind::STRING, mime_type));
+      }
+      wcva->OnDragEntered(metadata, locations);
+      break;
+    }
+    case ACTION_DRAG_LOCATION: {
+      wcva->OnDragUpdated(locations);
+      break;
+    }
+    case ACTION_DROP: {
+      base::string16 text_to_drop = ConvertJavaStringToUTF16(env, j_content);
+      DropData drop_data;
+      drop_data.did_originate_from_renderer = false;
+      for (base::string16 mime_type : mime_types) {

[dcheng, 2016/06/24 23:07:53]

const base::string16, otherwise this copies each member of the collection (same
thing above)

[hush (inactive), 2016/06/27 19:01:54]

Done.

+        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, locations);
+      break;
+    }
+    case ACTION_DRAG_EXITED:
+      wcva->OnDragExited();
+      break;
+    case ACTION_DRAG_ENDED:
+      break;
+  }
+}
+
 void ContentViewCoreImpl::RequestTextSurroundingSelection(
     int max_length,
     const base::Callback<