Add traffic annotation to CastChannelSendFunction::AsyncWorkStart().

Network traffic annotation is added to
CastChannelSendFunction::AsyncWorkStart().

Bug: 656607
Change-Id: I586c029890d07d922f159db10fbec27bc4d549b4
Reviewed-on: https://chromium-review.googlesource.com/911388
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Derek Cheng <imcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#536671}

extensions/browser/api/cast_channel/cast_channel_api.cc

@@ -408,10 +408,42 @@ void CastChannelSendFunction::AsyncWorkStart() {
     AsyncWorkCompleted();
     return;
   }
-  // TODO(https://crbug.com/656607): Add proper annotation.
+
+  net::NetworkTrafficAnnotationTag traffic_annotation =
+      net::DefineNetworkTrafficAnnotation("cast_channel_send", R"(
+        semantics {
+          sender: "Cast Channel"
+          description:
+            "A Cast protocol or application-level message sent to a Cast "
+            "device."
+          trigger:
+            "Triggered by user gesture from using Cast functionality, or "
+            "a webpage using the Presentation API, or "
+            "Cast device discovery internal logic."
+          data:
+            "A serialized Cast protocol or application-level protobuf message. "
+            "A non-exhaustive list of Cast protocol messages:\n"
+            "- Virtual connection requests,\n"
+            "- App availability / media status / receiver status requests,\n"
+            "- Launch / stop Cast session requests,\n"
+            "- Media commands, such as play/pause.\n"
+            "Application-level messages may contain data specific to the Cast "
+            "application."
+          destination: OTHER
+          destination_other:
+            "Data will be sent to a Cast device in local network."
+        }
+        policy {
+          cookies_allowed: NO
+          setting:
+            "This request cannot be disabled, but it would not be sent if user "
+            "does not connect a Cast device to the local network."
+          policy_exception_justification: "Not implemented."
+        })");
+
   socket->transport()->SendMessage(
       message_to_send, base::Bind(&CastChannelSendFunction::OnSend, this),
-      NO_TRAFFIC_ANNOTATION_BUG_656607);
+      traffic_annotation);
 }
 
 void CastChannelSendFunction::OnSend(int result) {

tools/metrics/histograms/enums.xml

@@ -43799,6 +43799,7 @@ Called by update_traffic_annotation_histograms.py.-->
   <int value="102819690" label="sync_file_system"/>
   <int value="102935425" label="safe_browsing_client_side_malware_detector"/>
   <int value="103133150" label="icon_cacher"/>
+  <int value="103172229" label="cast_channel_send"/>
   <int value="104798869" label="autofill_upload"/>
   <int value="105330607" label="profile_resetter_upload"/>
   <int value="106124561" label="ssl_hmac_channel_authenticator"/>

tools/traffic_annotation/summary/annotations.xml

@@ -29,6 +29,7 @@ Refer to README.md for content description and update process.
  <item id="bluetooth_socket" hash_code="94099818" type="0" content_hash_code="30932349" os_list="linux,windows" file_path="device/bluetooth/bluetooth_socket_net.cc"/>
  <item id="brandcode_config" hash_code="109679553" type="0" content_hash_code="128843792" os_list="linux,windows" file_path="chrome/browser/profile_resetter/brandcode_config_fetcher.cc"/>
  <item id="captive_portal_service" hash_code="88754904" type="0" content_hash_code="70737580" os_list="linux,windows" file_path="chrome/browser/captive_portal/captive_portal_service.cc"/>
+ <item id="cast_channel_send" hash_code="103172229" type="0" content_hash_code="33946302" os_list="linux,windows" file_path="extensions/browser/api/cast_channel/cast_channel_api.cc"/>
  <item id="cast_keep_alive_delegate" hash_code="134755844" type="0" content_hash_code="66118796" os_list="linux,windows" file_path="components/cast_channel/keep_alive_delegate.cc"/>
  <item id="cast_message_handler" hash_code="87558948" type="0" content_hash_code="49684899" os_list="linux,windows" file_path="components/cast_channel/cast_message_handler.cc"/>
  <item id="cast_socket" hash_code="115192205" type="0" content_hash_code="63056899" os_list="linux,windows" file_path="components/cast_channel/cast_socket.cc"/>