[TTS] Log diagnostic output log for Contextual Cards.

When Contextual Cards integration is enabled we now check for server
diagnostic data in the response and output it to the log when on a
debug build.

BUG=644934

Review-Url: https://codereview.chromium.org/2542813002
Cr-Commit-Position: refs/heads/master@{#435662}

chrome/browser/android/contextualsearch/contextual_search_delegate.cc

@@ -558,18 +558,16 @@ void ContextualSearchDelegate::DecodeSearchTermFromJsonResponse(
       base::FeatureList::IsEnabled(
           chrome::android::kContextualSearchSingleActions)) {
     // Any Contextual Cards integration.
-    // For testing purposes check if there was a Contextual Cards backend
-    // failure and flag that in the log.
+    // For testing purposes check if there was a diagnostic from Contextual
+    // Cards and output that into the log.
     // TODO(donnd): remove after full Contextual Cards integration.
-    bool contextual_cards_backend_responded = true;
-    dict->GetBoolean("coca_responded", &contextual_cards_backend_responded);
-    if (!contextual_cards_backend_responded) {
-      DVLOG(0) << "";
-      DVLOG(0) << "!!! CONTEXTUAL SEARCH WARNING !!!";
-      DVLOG(0)
-          << "The Contextual Cards backend did not respond to this "
-             "request!!! The backend server may not be configured or is down.";
-      DVLOG(0) << "";
+    std::string contextual_cards_diagnostic;
+    dict->GetString("diagnostic", &contextual_cards_diagnostic);
+    if (contextual_cards_diagnostic.empty()) {
+      DVLOG(0) << "No diagnostic data in the response.";
+    } else {
+      DVLOG(0) << "The Contextual Cards backend response: ";
+      DVLOG(0) << contextual_cards_diagnostic;
     }
   }
 }