Support dragging texts into Android WebView.

ui/base/BUILD.gn

Index: ui/base/BUILD.gn
diff --git a/ui/base/BUILD.gn b/ui/base/BUILD.gn
index 8a936fccdffa464891e8b615a541f37af86b1dc1..9f87a09e4205a8f66aa22213f67d1559f899317f 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -549,12 +549,17 @@ component("base") {
   }
 
   if (!toolkit_views && !use_aura) {
+    if (!is_android) {
+      sources -= [
+        "dragdrop/drag_drop_types.h",
+        "dragdrop/drop_target_event.cc",
+        "dragdrop/drop_target_event.h",
+        "dragdrop/os_exchange_data.cc",
+        "dragdrop/os_exchange_data.h",
+      ]
+    }
+
     sources -= [
-      "dragdrop/drag_drop_types.h",
-      "dragdrop/drop_target_event.cc",
-      "dragdrop/drop_target_event.h",
-      "dragdrop/os_exchange_data.cc",
-      "dragdrop/os_exchange_data.h",
       "nine_image_painter_factory.cc",
       "nine_image_painter_factory.h",
     ]
@@ -570,6 +575,11 @@ component("base") {
   }
 
   if (is_android && !use_aura) {
+    sources += [
+      "dragdrop/os_exchange_data_provider_android.cc",
+      "dragdrop/os_exchange_data_provider_android.h",
+    ]
+
     sources -= [
       "cursor/cursor_android.cc",
       "cursor/image_cursors.cc",