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..b63005bc640495a2a68243683897331337710007 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -570,6 +570,16 @@ component("base") {
   }
 
   if (is_android && !use_aura) {
+    sources += [
+      "dragdrop/drag_drop_types.h",

[aelias_OOO_until_Jul13, 2016/02/25 20:58:00]

Can we just remove all of the files without "_android" in the name from the "if
(!toolkit_views && !use_aura) { sources -= [" block below instead?  It looks
like these files are being added twice and removed once.

[hush (inactive), 2016/02/27 01:46:14]

Done.

+      "dragdrop/drop_target_event.cc",
+      "dragdrop/drop_target_event.h",
+      "dragdrop/os_exchange_data.cc",
+      "dragdrop/os_exchange_data.h",
+      "dragdrop/os_exchange_data_provider_android.cc",
+      "dragdrop/os_exchange_data_provider_android.h",
+    ]
+
     sources -= [
       "cursor/cursor_android.cc",
       "cursor/image_cursors.cc",