mac: Add support for asynchronous dictionary lookup

content/browser/renderer_host/text_input_client_message_filter.mm

Index: content/browser/renderer_host/text_input_client_message_filter.mm
diff --git a/content/browser/renderer_host/text_input_client_message_filter.mm b/content/browser/renderer_host/text_input_client_message_filter.mm
index 7af5a8ff2bd1d185bfbdb57307008d9f069f655f..61510511a793e7c587432ade0876bc22562e305a 100644
--- a/content/browser/renderer_host/text_input_client_message_filter.mm
+++ b/content/browser/renderer_host/text_input_client_message_filter.mm
@@ -26,6 +26,8 @@ bool TextInputClientMessageFilter::OnMessageReceived(
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP_EX(TextInputClientMessageFilter, message,
       *message_was_ok)
+    IPC_MESSAGE_HANDLER(TextInputClientReplyMsg_GotStringAtPoint,
+                        OnGotStringAtPoint)
     IPC_MESSAGE_HANDLER(TextInputClientReplyMsg_GotCharacterIndexForPoint,
                         OnGotCharacterIndexForPoint)
     IPC_MESSAGE_HANDLER(TextInputClientReplyMsg_GotFirstRectForRange,
@@ -39,6 +41,15 @@ bool TextInputClientMessageFilter::OnMessageReceived(
 
 TextInputClientMessageFilter::~TextInputClientMessageFilter() {}
 
+void TextInputClientMessageFilter::OnGotStringAtPoint(
+    const mac::AttributedStringCoder::EncodedString& encoded_string,
+    const gfx::Rect& rect) {
+  TextInputClientMac* service = TextInputClientMac::GetInstance();
+  NSAttributedString* string =
+      mac::AttributedStringCoder::Decode(&encoded_string);
+  service->GetStringAtPointReply(string, NSRectFromCGRect(rect.ToCGRect()));
+}
+
 void TextInputClientMessageFilter::OnGotCharacterIndexForPoint(size_t index) {
   TextInputClientMac* service = TextInputClientMac::GetInstance();
   // |index| could be WTF::notFound (-1) and its value is different from