tools: Remove wrapped JSON message in the DevTools parser (#40489)

Instead of outputing `{"_to": "...", "message": {"to": "...", ...}}` the
JSON message is simplified to `{"to": "...", ...}`. This is possible
since all valid devtools messages include a "to" or a "from" field.
These two fields will always be placed at the start of the serialized
message, with the rest of fields being sorted alphabetically.

Simplify detection of server or client message, removing the need to
pass the devtools port when reading a .pcap file. Now the pretty message
says "Server" and "Client" instead of "Servo" and "Firefox", which was
innacurate when inspecting one instance of Firefox from another.

Testing: Check with `mach test-scripts`

Signed-off-by: eri <eri@igalia.com>

etc/devtools_parser.py

@@ -66,7 +66,7 @@ def tshark(args, wait=False):
     return process.communicate()[0]
 
 
-def process_data(input, servo_port):
+def process_data(input):
     """Transform the raw output of tshark stdout into a manageable list."""
 
     # Split the input into lines.
@@ -123,58 +123,49 @@ def process_data(input, servo_port):
             message = rest[:length]
             rest = rest[length:]
             try:
-                records.append([time, port, message.decode()])
+                records.append([time, message.decode()])
             except UnicodeError as e:
                 print(f"[WARNING] Failed to decode message as UTF-8: {e}")
                 continue
 
-    # Process message records.
-    # `records` = [[date, port, message text]], e.g.
-    # `["2025-11-04T16:01:38.013100950+0100", "6080", "{...}"]`
-    result = []
-    for line in records:
-        time, port, text = line
-        # Port
-        port = "Servo" if port == servo_port else "Firefox"
-        # Data
-        result.append([time, port, len(result), text])
-
-    # `result` = [[date, endpoint, index, message text]], e.g.
-    # `["2025-11-04T16:01:38.013100950+0100", "Servo", 0, "{...}"]`
-    return result
+    # Return enumerated records.
+    # `records` = [[date, message text]], e.g.
+    # `["2025-11-04T16:01:38.013100950+0100", "{...}"]`
+    # `return` = [[date, message text, index]], e.g.
+    # `["2025-11-04T16:01:38.013100950+0100", "{...}", 0]`
+    return [(*line, i) for i, line in enumerate(records)]
 
 
-def parse_message(msg, *, json_output=False):
+def parse_message(msg, json_output=False):
     """Pretty print the JSON message, actor and timestamp.
     If `json_output` is True, output the JSON message in one line instead."""
 
-    time, sender, i, data = msg
-    from_servo = sender == "Servo"
-
-    colored_sender = colored(sender, "black", "on_yellow" if from_servo else "on_magenta", attrs=["bold"])
-    if not json_output:
-        print(f"\n{colored_sender} - {colored(i, 'blue')} - {colored(time, 'dark_grey')}")
+    time, data, i = msg
 
     try:
         content = json.loads(data)
-        if json_output:
-            if "to" in content:
-                # This is a request
-                print(json.dumps({"_to": content["to"], "message": content}, sort_keys=True))
-            elif "from" in content:
-                # This is a response
-                print(json.dumps({"_from": content["from"], "message": content}, sort_keys=True))
-            else:
-                assert False, "Message is neither a request nor a response"
-        else:
-            if from_servo and "from" in content:
-                print(colored(f"Actor: {content['from']}", "yellow"))
-            print(json.dumps(content, sort_keys=True, indent=4))
     except json.JSONDecodeError:
         print(f"Warning: Couldn't decode json\n{data}")
+        return
 
-    if not json_output:
-        print()
+    if json_output:
+        # Place from and to at the start so that it is easier to see which actor is involved
+        sorted_content = dict(
+            sorted(content.items(), key=lambda k: f"_{k[0]}" if k[0] == "from" or k[0] == "to" else k[0])
+        )
+        print(json.dumps(sorted_content))
+        return
+
+    is_server = "from" in content
+    colored_sender = (
+        colored("Server", "black", "on_yellow") if is_server else colored("Client", "on_magenta", attrs=["bold"])
+    )
+    pretty_json = json.dumps(content, sort_keys=True, indent=4)
+
+    print(f"""
+{colored_sender} - {colored(i, "blue")} - {colored(time, "dark_grey")}
+{pretty_json}
+""")
 
 
 if __name__ == "__main__":
@@ -199,7 +190,7 @@ if __name__ == "__main__":
         read_args = ["-r", args.use]
         data = tshark(read_args)
 
-    data = process_data(data, args.port)
+    data = process_data(data)
 
     # Set the range of messages to show
     min, max = 0, -2