Revert of [instrumentation] Turn inspector override "probes" return values into output parameters.

third_party/WebKit/Source/build/scripts/make_instrumenting_probes.py

 # Copyright 2017 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import ast
 import optparse
 import os.path
 import re
 import sys
 
@@ skipping 106 matching lines @@
         self.forward_declarations.sort()
 
 
 class Method(object):
     def __init__(self, source):
         match = re.match(r"(?:(\w+\*?)\s+)?(\w+)\s*\((.*)\)\s*;", source)
         if not match:
             sys.stderr.write("Cannot parse %s\n" % source)
             sys.exit(1)
 
+        self.return_type = match.group(1) or ""
         self.name = match.group(2)
-        self.is_scoped = not match.group(1)
-        if not self.is_scoped and match.group(1) != "void":
-            raise Exception("Instant probe must return void: %s" % self.name)
+        self.is_scoped = self.return_type == ""
 
         # Splitting parameters by a comma, assuming that attribute lists contain no more than one attribute.
         self.params = map(Parameter, map(str.strip, match.group(3).split(",")))
 
+        self.returns_value = self.return_type != "" and self.return_type != "void"
+        if self.return_type == "bool":
+            self.default_return_value = "false"
+        elif self.returns_value:
+            sys.stderr.write("Can only return bool: %s\n" % self.name)
+            sys.exit(1)
+
 
 class Parameter(object):
     def __init__(self, source):
         self.options = []
         match, source = match_and_consume(r"\[(\w*)\]", source)
         if match:
             self.options.append(match.group(1))
 
         parts = map(str.strip, source.split("="))
         self.default_value = parts[1] if len(parts) != 1 else None
@@ skipping 55 matching lines @@
             unused_probes.discard(probe)
             if probe not in all_pidl_probes:
                 raise Exception('Probe %s is not declared in PIDL file' % probe)
             observers_by_probe.setdefault(probe, set()).add(observer_name)
     if unused_probes:
         raise Exception("Unused probes: %s" % unused_probes)
 
     for f in files:
         for probe in f.declarations:
             probe.agents = observers_by_probe[probe.name]
+            if probe.returns_value and len(probe.agents) > 1:
+                raise Exception("Can only return value from a single observer: %s\n" % probe.name)
     return all_observers
 
 
 cmdline_parser = optparse.OptionParser()
 cmdline_parser.add_option("--output_dir")
 cmdline_parser.add_option("--config")
 
 try:
     arg_options, arg_values = cmdline_parser.parse_args()
     if len(arg_values) != 1:
@@ skipping 37 matching lines @@
 sink_h_file = open(output_dirpath + "/" + to_singular(base_name) + "Sink.h", "w")
 sink_h_file.write(sink_h_template.render(template_context))
 sink_h_file.close()
 
 for f in files:
     template_context["file"] = f
     h_template = jinja_env.get_template("/InstrumentingProbesInl.h.tmpl")
     h_file = open(output_dirpath + "/" + f.header_name + ".h", "w")
     h_file.write(h_template.render(template_context))
     h_file.close()