Add Mojo API for Blink hit testing

content/browser/frame_host/input/legacy_ipc_frame_input_handler.cc

Index: content/browser/frame_host/input/legacy_ipc_frame_input_handler.cc
diff --git a/content/browser/frame_host/input/legacy_ipc_frame_input_handler.cc b/content/browser/frame_host/input/legacy_ipc_frame_input_handler.cc
index 51dc7f1d416495e24f581f3f883cda63d357b3b6..6fa778e3ed8a93d8b8124198f0b8053e278244bd 100644
--- a/content/browser/frame_host/input/legacy_ipc_frame_input_handler.cc
+++ b/content/browser/frame_host/input/legacy_ipc_frame_input_handler.cc
@@ -121,6 +121,12 @@ void LegacyIPCFrameInputHandler::CollapseSelection() {
   SendInput(base::MakeUnique<InputMsg_CollapseSelection>(routing_id_));
 }
 
+void LegacyIPCFrameInputHandler::HitTestFrameAt(
+    const gfx::PointF& point,
+    HitTestFrameAtCallback callback) {
+  // We do not support this API over old IPC.

[rjkroege, 2017/06/26 18:29:52]

NOTREACHED(); ?

+}
+
 void LegacyIPCFrameInputHandler::SelectRange(const gfx::Point& point,
                                              const gfx::Point& extent) {
   SendInput(base::MakeUnique<InputMsg_SelectRange>(routing_id_, point, extent));