ml: add mojo API for language identification

Also roll the edits on mojom in CL:
https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2291868

BUG=chromium:1086044
TEST=on device (eve), can call langid function
TEST=in the chrome://machine-learning-internal webpage.

Change-Id: I8abdeac7e318397069bf7961ad4ae43667df15eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2289573Reviewed-by: Andrew Moylan <amoylan@chromium.org>
Reviewed-by: Sam McNally <sammc@chromium.org>
Commit-Queue: Honglin Yu <honglinyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791737}

chromeos/services/machine_learning/public/cpp/fake_service_connection.cc

@@ -211,6 +211,16 @@ void FakeServiceConnectionImpl::HandleSuggestSelectionCall(
   std::move(callback).Run(std::move(selection));
 }
 
+void FakeServiceConnectionImpl::HandleFindLanguagesCall(
+    std::string request,
+    mojom::TextClassifier::FindLanguagesCallback callback) {
+  std::vector<mojom::TextLanguagePtr> languages;
+  for (auto const& language : find_languages_result_) {
+    languages.emplace_back(language.Clone());
+  }
+  std::move(callback).Run(std::move(languages));
+}
+
 void FakeServiceConnectionImpl::SetOutputAnnotation(
     const std::vector<mojom::TextAnnotationPtr>& annotations) {
   annotate_result_.clear();
@@ -224,6 +234,14 @@ void FakeServiceConnectionImpl::SetOutputSelection(
   suggest_selection_result_ = selection.Clone();
 }
 
+void FakeServiceConnectionImpl::SetOutputLanguages(
+    const std::vector<mojom::TextLanguagePtr>& languages) {
+  find_languages_result_.clear();
+  for (auto const& language : languages) {
+    find_languages_result_.emplace_back(language.Clone());
+  }
+}
+
 void FakeServiceConnectionImpl::SetOutputHandwritingRecognizerResult(
     const mojom::HandwritingRecognizerResultPtr& result) {
   handwriting_result_ = result.Clone();
@@ -245,6 +263,14 @@ void FakeServiceConnectionImpl::SuggestSelection(
       base::Unretained(this), std::move(request), std::move(callback)));
 }
 
+void FakeServiceConnectionImpl::FindLanguages(
+    const std::string& text,
+    mojom::TextClassifier::FindLanguagesCallback callback) {
+  ScheduleCall(base::BindOnce(
+      &FakeServiceConnectionImpl::HandleFindLanguagesCall,
+      base::Unretained(this), text, std::move(callback)));
+}
+
 void FakeServiceConnectionImpl::Recognize(
     mojom::HandwritingRecognitionQueryPtr query,
     mojom::HandwritingRecognizer::RecognizeCallback callback) {

chromeos/services/machine_learning/public/cpp/fake_service_connection.h

@@ -120,6 +120,10 @@ class FakeServiceConnectionImpl : public ServiceConnection,
   // selection.
   void SetOutputSelection(const mojom::CodepointSpanPtr& selection);
 
+  // Call SetOutputLanguages() before FindLanguages() to set the output
+  // languages.
+  void SetOutputLanguages(const std::vector<mojom::TextLanguagePtr>& languages);
+
   // Call SetOutputHandwritingRecognizerResult() before Recognize() to set the
   // output of handwriting.
   void SetOutputHandwritingRecognizerResult(
@@ -134,6 +138,11 @@ class FakeServiceConnectionImpl : public ServiceConnection,
       mojom::TextSuggestSelectionRequestPtr request,
       mojom::TextClassifier::SuggestSelectionCallback callback) override;
 
+  // mojom::TextClassifier:
+  void FindLanguages(
+      const std::string& text,
+      mojom::TextClassifier::FindLanguagesCallback callback) override;
+
   // mojom::HandwritingRecognizer:
   void Recognize(
       mojom::HandwritingRecognitionQueryPtr query,
@@ -159,6 +168,9 @@ class FakeServiceConnectionImpl : public ServiceConnection,
   void HandleSuggestSelectionCall(
       mojom::TextSuggestSelectionRequestPtr request,
       mojom::TextClassifier::SuggestSelectionCallback callback);
+  void HandleFindLanguagesCall(
+      std::string text,
+      mojom::TextClassifier::FindLanguagesCallback callback);
   void HandleLoadHandwritingModel(
       mojo::PendingReceiver<mojom::HandwritingRecognizer> receiver,
       mojom::MachineLearningService::LoadHandwritingModelCallback callback);
@@ -177,6 +189,7 @@ class FakeServiceConnectionImpl : public ServiceConnection,
   mojom::ExecuteResult execute_result_;
   std::vector<mojom::TextAnnotationPtr> annotate_result_;
   mojom::CodepointSpanPtr suggest_selection_result_;
+  std::vector<mojom::TextLanguagePtr> find_languages_result_;
   mojom::HandwritingRecognizerResultPtr handwriting_result_;
 
   bool async_mode_;

chromeos/services/machine_learning/public/cpp/service_connection_unittest.cc

@@ -315,6 +315,51 @@ TEST_F(ServiceConnectionTest,
   ASSERT_TRUE(infer_callback_done);
 }
 
+// Tests the fake ML service for text classifier language identification.
+TEST_F(ServiceConnectionTest,
+       FakeServiceConnectionForTextClassifierFindLanguages) {
+  mojo::Remote<mojom::TextClassifier> text_classifier;
+  bool callback_done = false;
+  FakeServiceConnectionImpl fake_service_connection;
+  ServiceConnection::UseFakeServiceConnectionForTesting(
+      &fake_service_connection);
+
+  std::vector<mojom::TextLanguagePtr> languages;
+  languages.emplace_back(mojom::TextLanguage::New("en", 0.9));
+  languages.emplace_back(mojom::TextLanguage::New("fr", 0.1));
+  fake_service_connection.SetOutputLanguages(languages);
+
+  ServiceConnection::GetInstance()->LoadTextClassifier(
+      text_classifier.BindNewPipeAndPassReceiver(),
+      base::BindOnce(
+          [](bool* callback_done, mojom::LoadModelResult result) {
+            EXPECT_EQ(result, mojom::LoadModelResult::OK);
+            *callback_done = true;
+          },
+          &callback_done));
+  base::RunLoop().RunUntilIdle();
+  ASSERT_TRUE(callback_done);
+  ASSERT_TRUE(text_classifier.is_bound());
+
+  std::string input_text = "dummy input text";
+  bool infer_callback_done = false;
+  text_classifier->FindLanguages(
+      input_text, base::Bind(
+                      [](bool* infer_callback_done,
+                         std::vector<mojom::TextLanguagePtr> languages) {
+                        *infer_callback_done = true;
+                        // Check if the suggestion is correct.
+                        ASSERT_EQ(languages.size(), 2ul);
+                        EXPECT_EQ(languages[0]->locale, "en");
+                        EXPECT_EQ(languages[0]->confidence, 0.9f);
+                        EXPECT_EQ(languages[1]->locale, "fr");
+                        EXPECT_EQ(languages[1]->confidence, 0.1f);
+                      },
+                      &infer_callback_done));
+  base::RunLoop().RunUntilIdle();
+  ASSERT_TRUE(infer_callback_done);
+}
+
 // Tests the fake ML service for handwriting.
 TEST_F(ServiceConnectionTest, FakeHandWritingRecognizerWithSpec) {
   mojo::Remote<mojom::HandwritingRecognizer> recognizer;

chromeos/services/machine_learning/public/mojom/machine_learning_service.mojom

@@ -33,24 +33,29 @@ enum LoadModelResult {
 };
 
 // Top-level interface between Chromium and the ML Service daemon.
+// Next ordinal: 6
 interface MachineLearningService {
+  // Binds another pipe to this instance.
+  Clone@5(pending_receiver<MachineLearningService> receiver);
+
   // The BuiltinModelId inside BuiltinModelSpec is used to specify the model to
   // be loaded.
-  LoadBuiltinModel(BuiltinModelSpec spec, pending_receiver<Model> receiver)
+  LoadBuiltinModel@0(BuiltinModelSpec spec, pending_receiver<Model> receiver)
       => (LoadModelResult result);
   // The FlatbufferModelSpec contains both of the flatbuffer content and the
   // metadata.
-  LoadFlatBufferModel(FlatBufferModelSpec spec,
+  LoadFlatBufferModel@1(FlatBufferModelSpec spec,
                         pending_receiver<Model> receiver)
       => (LoadModelResult result);
   // Create a new TextClassifier.
-  LoadTextClassifier(pending_receiver<TextClassifier> receiver)
+  LoadTextClassifier@2(pending_receiver<TextClassifier> receiver)
       => (LoadModelResult result);
   // Create and initialize a handwriting recognizer.
-  LoadHandwritingModel(pending_receiver<HandwritingRecognizer> receiver)
+  LoadHandwritingModel@3(pending_receiver<HandwritingRecognizer> receiver)
       => (LoadModelResult result);
-  // Create and initialize a handwriting recognizer with given |spec|.
-  LoadHandwritingModelWithSpec(HandwritingRecognizerSpec spec,
+  // Create and initialize a handwriting recognizer with given `spec`.
+  LoadHandwritingModelWithSpec@4(
+      HandwritingRecognizerSpec spec,
       pending_receiver<HandwritingRecognizer> receiver)
       => (LoadModelResult result);
 };

chromeos/services/machine_learning/public/mojom/text_classifier.mojom

@@ -22,20 +22,6 @@ module chromeos.machine_learning.mojom;
 //       under mojo folder, that is, "mojo/public/mojom/base/time.mojom".
 import "mojo/public/mojom/base/time.mojom";
 
-// These values are persisted to logs. Entries should not be renumbered and
-// numeric values should never be reused.
-enum TextAnnotationResult {
-  OK = 0,
-  ERROR = 1,
-};
-
-// These values are persisted to logs. Entries should not be renumbered and
-// numeric values should never be reused.
-enum SuggestSelectionResult {
-  OK = 0,
-  ERROR = 1,
-};
-
 // Enum for specifying the annotation usecase.
 // Must be consistent with `AnnotationUsecase` in model.fb in libtextclassifier.
 enum AnnotationUsecase {
@@ -138,6 +124,14 @@ struct TextSuggestSelectionRequest {
   AnnotationUsecase annotation_usecase@4 = ANNOTATION_USECASE_SMART;
 };
 
+// Represent a language detection result.
+struct TextLanguage {
+  // The BCP-47 language code like "en", "fr", "zh" etc.
+  string locale;
+  // The confidence score of the language detected (range: 0~1).
+  float confidence;
+};
+
 // Used to annotate entities within text strings.
 interface TextClassifier {
   // Annotate a text string and returns the detected substrings and possible
@@ -151,4 +145,10 @@ interface TextClassifier {
   // UTF8 codepoints (not bytes).
   SuggestSelection@1(TextSuggestSelectionRequest request) =>
       (CodepointSpan outputs);
+  // Identify the languages the text is possibly written in.
+  // The returned results are sorted according to the confidence score, from the
+  // highest to the lowest.
+  // The maximum number of results returned is determined internally.
+  // Will return an empty array if the language can not be determined.
+  FindLanguages@2(string text) => (array<TextLanguage> outputs);
 };