[Omnibox][ML] Add signal normalization.

(cherry picked from commit 1ac78e2)

Bug: 1457678,b/287323698
Change-Id: Ifbcb7301176a128be1886265a31bdb35dc90143c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4633630
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Commit-Queue: Jun Zou <junzou@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1161315}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4646671
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/5845@{#110}
Cr-Branched-From: 5a5dff6-refs/heads/main@{#1160321}

components/omnibox/browser/autocomplete_scoring_model_handler.cc

@@ -294,6 +294,13 @@ AutocompleteScoringModelHandler::ExtractInputFromScoringSignals(
                 : kDefaultMissingValue;
     }
 
+    // Normalize signal if configured.
+    if (scoring_signal_spec.has_norm_upper_boundary()) {
+      float upper_boundary = scoring_signal_spec.norm_upper_boundary();
+      DCHECK_GT(upper_boundary, 0);
+      val = std::clamp(*val, -upper_boundary, upper_boundary) / upper_boundary;
+    }
+
     model_input.push_back(*val);
   }
   DCHECK_EQ(static_cast<size_t>(model_input.size()),

components/omnibox/browser/autocomplete_scoring_model_handler_unittest.cc

@@ -141,10 +141,11 @@ class AutocompleteScoringModelHandlerTest : public testing::Test {
 
 TEST_F(AutocompleteScoringModelHandlerTest,
        ExtractInputFromScoringSignalsTest) {
-  // Metadata with three scoring signal specifications.
+  // Metadata with scoring signal specifications.
   AutocompleteScoringModelMetadata model_metadata;
   *model_metadata.add_scoring_signal_specs() = CreateScoringSignalSpec(
       optimization_guide::proto::SCORING_SIGNAL_TYPE_LENGTH_OF_URL);
+  model_metadata.mutable_scoring_signal_specs(0)->set_norm_upper_boundary(50);
   // Signal with log2 transformation.
   *model_metadata.add_scoring_signal_specs() = CreateScoringSignalSpec(
       optimization_guide::proto::
@@ -160,20 +161,26 @@ TEST_F(AutocompleteScoringModelHandlerTest,
           SCORING_SIGNAL_TYPE_ELAPSED_TIME_LAST_SHORTCUT_VISIT_SEC,
       /*transformation=*/absl::nullopt,
       /*min_val=*/0, /*max_val=*/absl::nullopt, /*missing_val=*/-2);
+  // Clamped by upper boundary.
+  *model_metadata.add_scoring_signal_specs() = CreateScoringSignalSpec(
+      optimization_guide::proto::SCORING_SIGNAL_TYPE_TYPED_COUNT);
+  model_metadata.mutable_scoring_signal_specs(4)->set_norm_upper_boundary(100);
 
   // Scoring signals.
   ScoringSignals scoring_signals;
   scoring_signals.set_length_of_url(10);
   scoring_signals.set_elapsed_time_last_visit_secs(32767);
   scoring_signals.set_elapsed_time_last_shortcut_visit_sec(-200);
+  scoring_signals.set_typed_count(150);
 
   const auto input_signals = model_handler_->ExtractInputFromScoringSignals(
       scoring_signals, model_metadata);
-  ASSERT_EQ(input_signals.size(), 4u);
-  EXPECT_THAT(input_signals[0], 10);
+  ASSERT_EQ(input_signals.size(), 5u);
+  EXPECT_THAT(input_signals[0], 0.2);  // Normalized signal.
   EXPECT_THAT(input_signals[1], 15);
   EXPECT_NEAR(input_signals[2], 0.3792, 0.0001);
   EXPECT_THAT(input_signals[3], -2);
+  EXPECT_NEAR(input_signals[4], 1.0f, 0.0001);  // Clamped and normalized.
 }
 
 TEST_F(AutocompleteScoringModelHandlerTest, GetBatchModelInputTest) {

components/optimization_guide/proto/autocomplete_scoring_model_metadata.proto

@@ -59,6 +59,8 @@ message ScoringSignalSpec {
   optional float min_value = 4;
   // Maximum value of valid signals.
   optional float max_value = 5;
+  // The upper boundary for normalization.
+  optional float norm_upper_boundary = 6;
 }
 
 // The message contains a set of params to run a specific autocomplete scoring