ambient: change attribution text

Concatenate metadata_line_{1,2} with spaces.
Ignore metadata_line_3.

BUG=b:170360468

Cq-Include-Trybots: luci.chrome.try:linux-chromeos-chrome
Change-Id: I3151728baac2d3b44330a54b1684844d83562def
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2468839Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Reviewed-by: Tao Wu <wutao@chromium.org>
Reviewed-by: Meilin Wang <meilinw@chromium.org>
Commit-Queue: Jeffrey Young <cowmoo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817354}

ash/ambient/backdrop/ambient_backend_controller_impl.cc

@@ -90,37 +90,19 @@ std::unique_ptr<network::ResourceRequest> CreateResourceRequest(
   return resource_request;
 }
 
-std::string BuildCuratedTopicDetails(
-    const backdrop::ScreenUpdate::Topic& topic) {
-  if (topic.has_metadata_line_1() && topic.has_metadata_line_2()) {
-    // Uses a space as the separator between.
-    return topic.metadata_line_1() + " " + topic.metadata_line_2();
-  } else if (topic.has_metadata_line_1()) {
-    return topic.metadata_line_1();
-  } else if (topic.has_metadata_line_2()) {
-    return topic.metadata_line_2();
-  } else {
-    return std::string();
-  }
-}
-
-std::string BuildPersonalTopicDetails(
-    const backdrop::ScreenUpdate::Topic& topic) {
-  // |metadata_line_1| contains the album name.
-  return topic.has_metadata_line_1() ? topic.metadata_line_1() : std::string();
-}
-
-void BuildBackdropTopicDetails(
-    const backdrop::ScreenUpdate::Topic& backdrop_topic,
-    AmbientModeTopic& ambient_topic) {
-  switch (backdrop_topic.topic_type()) {
-    case backdrop::TopicSource::PERSONAL_PHOTO:
-      ambient_topic.details = BuildPersonalTopicDetails(backdrop_topic);
-      break;
-    default:
-      ambient_topic.details = BuildCuratedTopicDetails(backdrop_topic);
-      break;
+std::string BuildBackdropTopicDetails(
+    const backdrop::ScreenUpdate::Topic& backdrop_topic) {
+  std::string result;
+  if (backdrop_topic.has_metadata_line_1())
+    result += backdrop_topic.metadata_line_1();
+
+  if (backdrop_topic.has_metadata_line_2()) {
+    if (!result.empty())
+      result += " ";
+    result += backdrop_topic.metadata_line_2();
   }
+  // Do not include metadata_line_3.
+  return result;
 }
 
 AmbientModeTopicType ToAmbientModeTopicType(
@@ -240,8 +222,7 @@ ScreenUpdate ToScreenUpdate(
               backdrop_topic.related_topic().url();
         }
       }
-
-      BuildBackdropTopicDetails(backdrop_topic, ambient_topic);
+      ambient_topic.details = BuildBackdropTopicDetails(backdrop_topic);
       screen_update.next_topics.emplace_back(ambient_topic);
     }
   }