Pass lower case text to text annotator.

There is a issue with text classifier that some capitalized words are not
annotated properly. Convert the text to lower case for now.

Bug: b/159756246
Test: manual test
Change-Id: I66d355f503890a2b1d3c183853210fb1fd4aa8a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2261818Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Yue Li <updowndota@chromium.org>
Commit-Queue: Li Lin <llin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782080}

chromeos/components/quick_answers/understanding/intent_generator.cc

@@ -6,6 +6,7 @@
 
 #include <map>
 
+#include "base/i18n/case_conversion.h"
 #include "base/no_destructor.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chromeos/components/quick_answers/quick_answers_model.h"
@@ -118,7 +119,12 @@ void IntentGenerator::LoadModelCallback(const QuickAnswersRequest& request,
   if (text_classifier_) {
     TextAnnotationRequestPtr text_annotation_request =
         machine_learning::mojom::TextAnnotationRequest::New();
-    text_annotation_request->text = request.selected_text;
+
+    // TODO(b/159664194): There is a issue with text classifier that some
+    // capitalized words are not annotated properly. Convert the text to lower
+    // case for now. Clean up after the issue is fixed.
+    text_annotation_request->text = base::UTF16ToUTF8(
+        base::i18n::ToLower(base::UTF8ToUTF16(request.selected_text)));
     text_annotation_request->default_locales =
         request.context.device_properties.language;