[PWA] Fix PWA mobile model metadata processing issues

Add a check for input_context to prevent crash when input_context is null after reaching custom input processor.

Enforce input context based custom input features to be float only.

Bug: b/278782487
Change-Id: Ia75a9a562a8fb3c3821156c076df373f0d260a4e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4611100
Reviewed-by: Ella Ge <eirage@chromium.org>
Commit-Queue: Hailey Wang <haileywang@google.com>
Reviewed-by: Siddhartha S <ssid@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1158417}

components/segmentation_platform/internal/execution/processing/custom_input_processor.cc

@@ -240,16 +240,20 @@ bool CustomInputProcessor::AddFromInputContext(
     input_name = custom_input_iter->second;
   }
 
-  auto input_context_iter = input_context->metadata_args.find(input_name);
-  if (input_context_iter == input_context->metadata_args.end()) {
+  absl::optional<processing::ProcessedValue> input_context_value;
+  if (input_context) {
+    input_context_value = input_context->GetMetadataArgument(input_name);
+  }
+
+  if (!input_context || !input_context_value.has_value()) {
     feature_processor_state->SetError(
         stats::FeatureProcessingError::kCustomInputError,
         "The model expects an input '" + input_name +
             "' which wasn't found in the input context.");
     return false;
   }
 
-  out_tensor.emplace_back(input_context_iter->second);
+  out_tensor.emplace_back(input_context_value.value());
   return true;
 }
 

components/webapps/browser/android/ambient_badge_manager.cc

@@ -226,8 +226,10 @@ void AmbientBadgeManager::MaybeShowAmbientBadgeSmart(
   auto input_context =
       base::MakeRefCounted<segmentation_platform::InputContext>();
   input_context->metadata_args.emplace("url", validated_url_);
-  input_context->metadata_args.emplace("maskable_icon",
-                                       a2hs_params_->HasMaskablePrimaryIcon());
+  input_context->metadata_args.emplace(
+      "maskable_icon",
+      segmentation_platform::processing::ProcessedValue::FromFloat(
+          a2hs_params_->HasMaskablePrimaryIcon()));
   segmentation_platform_service_->GetClassificationResult(
       segmentation_platform::kWebAppInstallationPromoKey, prediction_options,
       input_context,