Pass ID of the calling extension to the native messaging host.

chrome/test/data/native_messaging/native_hosts/echo.py

Index: chrome/test/data/native_messaging/native_hosts/echo.py
diff --git a/chrome/test/data/native_messaging/native_hosts/echo.py b/chrome/test/data/native_messaging/native_hosts/echo.py
index d0be74bdfe9cb84b8767afe5f63676a2412c89f4..96c19f71cb25479175908c9f35f91e4161e4c4d4 100755
--- a/chrome/test/data/native_messaging/native_hosts/echo.py
+++ b/chrome/test/data/native_messaging/native_hosts/echo.py
@@ -12,6 +12,11 @@ import struct
 def Main():
   message_number = 0
 
+  if len(sys.argv) < 2:
+    sys.stderr.write("URL of the calling application is not specified.\n")
+    return;
+  caller_url = sys.argv[1]
+
   while 1:
     # Read the message type (first 4 bytes).
     text_length_bytes = sys.stdin.read(4)
@@ -27,8 +32,8 @@ def Main():
 
     message_number += 1
 
-    response = '{{"id": {0}, "echo": {1}}}'.format(message_number,
-                                                   text).encode('utf-8')
+    response = '{{"id": {0}, "echo": {1}, "caller_url": "{2}"}}'.format(
+        message_number, text, caller_url).encode('utf-8')
 
     try:
       sys.stdout.write(struct.pack("I", len(response)))