Tool added to extract network traffic annotations.

tools/clang/traffic_annotation_extractor/tests/expected_outputs/______components_autofill_core_browser_autofill_download_manager_cc(68).txt

+../../components/autofill/core/browser/autofill_download_manager.cc
+(anonymous namespace)::GetNetworkTrafficAnnotation
+68
+autofill_upload
+
+      semantics {
+        sender: "Autofill"
+        description:
+          "Chromium relies on crowd-sourced field type classifications to "
+          "help it automatically fill in web forms. If the feature is "
+          "enabled, Chromium will send a non-identifying description of the "
+          "form to Google's servers along with the type of data Chromium "
+          "observed being given to the form. I.e., if you entered your first "
+          "name into a form field, Chromium will 'vote' for that form field "
+          "being a first name field."
+        trigger: "User submits a web form."
+        data:
+          "Hashed descriptions of the form and its fields along with type of "
+          "data given to each field, if recognized from the user's "
+          "profile(s). 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
+          }
+        }
+      }