Tool added to extract network traffic annotations.

tools/clang/traffic_annotation_extractor/tests/expected_outputs/______components_autofill_core_browser_autofill_download_manager_cc(36).txt

+../../components/autofill/core/browser/autofill_download_manager.cc
+(anonymous namespace)::GetNetworkTrafficAnnotation
+36
+autofill_query
+
+        semantics {
+          sender: "Autofill"
+          description:
+            "Chromium can automatically fill in web forms. If the feature is "
+            "enabled, Chromium will send a non-identifying description of the "
+            "form to Google's servers, which will respond with the type of "
+            "data required by each of the form's fields, if known. I.e., if a "
+            "field expects to receive a name, phone number, street address, "
+            "etc."
+          trigger: "User encounters a web form."
+          data:
+            "Hashed descriptions of the form and its fields. User data is not "
+            "sent."
+          destination: GOOGLE_OWNED_SERVICE
+        }
+        policy {
+          cookies_allowed: false
+          setting:
+            "You can enable or disable this feature via 'Enable autofill to "
+            "fill out web forms in a single click.' in Chromium's settings "
+            "under 'Passwords and forms'. The feature is enabled by default."
+          chrome_policy {
+            AutofillEnabled {
+                policy_options {mode: MANDATORY}
+                AutofillEnabled: false
+            }
+          }
+        }