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 d70219a71ef275a274ba0f2cb91ad79fe20f34a8..04c30ba44da0d8bdf24b4b3b567bc7e4c0be63cd 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -54,6 +54,8 @@
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/android/view_android.h"
 #include "ui/android/window_android.h"
+#include "ui/base/dragdrop/drop_target_event.h"
+#include "ui/base/dragdrop/os_exchange_data_provider_android.h"
 #include "ui/events/android/motion_event_android.h"
 #include "ui/gfx/android/java_bitmap.h"
 #include "ui/gfx/geometry/point_conversions.h"
@@ -1409,6 +1411,72 @@ void ContentViewCoreImpl::SetBackgroundOpaque(JNIEnv* env,
   }
 }
 
+void ContentViewCoreImpl::OnDragEntered(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj,
+    int x,
+    int y,
+    int screen_x,
+    int screen_y) {
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+
+  ui::OSExchangeData data(new ui::OSExchangeDataProviderAndroid());

[dcheng, 2016/02/25 01:18:49]

Will there be a followup patch to address the fact that the types are not
plumbed through?

[hush (inactive), 2016/02/25 02:40:48]

Types are sort of plumbed through. We only support "string" format for now. So
we will return true for OSExchangeData::HasString and false for other types.
Webview won't get any drag drop related events if the drop data type is not
text. (See AwContents#onDragEvent. Returning false on "ACTION_DRAG_STARTED" will
ensure there won't be any subsequence DragEvents)


Yes, there will be a followup to support dragging image file URIs into webview.

[dcheng, 2016/02/25 21:13:38]

I don't think I follow: I don't see how the types are plumbed through at all
atm. Since we don't know what the contents of the drop are yet,
OSExchangeDataProviderAndroid will be unpopulated. So PrepareDropData will
always prepare a drop data that's empty.

[hush (inactive), 2016/02/27 01:47:22]

Sorry yeah you're right. I just updated the logic here. I will set an empty
string when on DRAG_ENTERED event to indicate the data type is string.

+  ui::DropTargetEvent event(
+      data, gfx::Point(x, y), gfx::Point(screen_x, screen_y),
+      ui::DragDropTypes::DRAG_COPY);  // Android drag and drop does only copy.
+
+  wcva->OnDragEntered(event);
+}
+
+void ContentViewCoreImpl::OnDragUpdated(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj,
+    int x,
+    int y,
+    int screen_x,
+    int screen_y) {
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+
+  ui::OSExchangeData data(new ui::OSExchangeDataProviderAndroid());
+  ui::DropTargetEvent event(
+      data, gfx::Point(x, y), gfx::Point(screen_x, screen_y),
+      ui::DragDropTypes::DRAG_COPY);  // Android drag and drop does only copy.
+
+  wcva->OnDragUpdated(event);
+}
+
+void ContentViewCoreImpl::OnPerformDrop(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj,
+    int x,
+    int y,
+    int screen_x,
+    int screen_y,
+    const base::android::JavaParamRef<jstring>& content) {
+  base::string16 text_to_drop = ConvertJavaStringToUTF16(env, content);
+
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+
+  ui::OSExchangeData data(new ui::OSExchangeDataProviderAndroid());
+  data.SetString(text_to_drop);
+  ui::DropTargetEvent event(data, gfx::Point(x, y),
+                            gfx::Point(screen_x, screen_y),
+                            ui::DragDropTypes::DRAG_COPY);
+
+  wcva->OnPerformDrop(event);
+}
+
+void ContentViewCoreImpl::OnDragExited(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jobj) {
+  WebContentsViewAndroid* wcva = static_cast<WebContentsViewAndroid*>(
+      static_cast<WebContentsImpl*>(web_contents())->GetView());
+  wcva->OnDragExited();
+}
+
 void ContentViewCoreImpl::RequestTextSurroundingSelection(
     int max_length,
     const base::Callback<