Add class for holding information about calling app

This CallingAppInfo class contains calling app package and app
signature. Since Credential manager pings multiple providers, this
is a performance optimization so that each provider does not need to
query app signatures separately.

Test: Built & deployed locally
Bug: 253155222
API-Coverage-Bug: 247549381

Change-Id: Iec580a252c4f27b92d02fe5c50e1085ee23f8f4b

core/api/current.txt

@@ -39573,6 +39573,15 @@ package android.service.credentials {
     field @NonNull public static final android.os.Parcelable.Creator<android.service.credentials.BeginGetCredentialsResponse> CREATOR;
   }
 
+  public final class CallingAppInfo implements android.os.Parcelable {
+    ctor public CallingAppInfo(@NonNull String, @NonNull java.util.Set<android.content.pm.Signature>);
+    method public int describeContents();
+    method @NonNull public String getPackageName();
+    method @NonNull public java.util.Set<android.content.pm.Signature> getSignatures();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.service.credentials.CallingAppInfo> CREATOR;
+  }
+
   public final class CreateCredentialRequest implements android.os.Parcelable {
     ctor public CreateCredentialRequest(@NonNull String, @NonNull String, @NonNull android.os.Bundle);
     method public int describeContents();

core/java/android/service/credentials/CallingAppInfo.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.service.credentials;
+
+import android.annotation.NonNull;
+import android.content.pm.Signature;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.util.ArraySet;
+
+import com.android.internal.util.AnnotationValidations;
+import com.android.internal.util.Preconditions;
+
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * Information pertaining to the calling application, including the package name and a list of
+ * app signatures.
+ */
+public final class CallingAppInfo implements Parcelable {
+    @NonNull private final String mPackageName;
+    @NonNull private final Set<Signature> mSignatures;
+
+    /**
+     * Constructs a new instance.
+     *
+     * @throws IllegalArgumentException If {@code packageName} is null or empty.
+     * @throws NullPointerException If {@code signatures} is null.
+     */
+    public CallingAppInfo(@NonNull String packageName,
+            @NonNull Set<Signature> signatures) {
+        mPackageName = Preconditions.checkStringNotEmpty(packageName,
+                "packageName must not be null or empty");
+        mSignatures = Objects.requireNonNull(signatures);
+    }
+
+    private CallingAppInfo(@NonNull Parcel in) {
+        final ClassLoader boot = Object.class.getClassLoader();
+        mPackageName = in.readString8();
+        ArraySet<Signature> signatures = (ArraySet<Signature>) in.readArraySet(boot);
+        mSignatures = signatures == null ? new ArraySet<>() : signatures;
+    }
+
+    public static final @NonNull Creator<CallingAppInfo> CREATOR = new Creator<CallingAppInfo>() {
+        @Override
+        public CallingAppInfo createFromParcel(Parcel in) {
+            return new CallingAppInfo(in);
+        }
+
+        @Override
+        public CallingAppInfo[] newArray(int size) {
+            return new CallingAppInfo[size];
+        }
+    };
+
+    /** Returns the package name of the source of this info. */
+    @NonNull public String getPackageName() {
+        return mPackageName;
+    }
+
+    /** Returns the Set of signatures belonging to the app */
+    @NonNull public Set<Signature> getSignatures() {
+        return mSignatures;
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
+        dest.writeString8(mPackageName);
+        dest.writeArraySet(new ArraySet<>(mSignatures));
+    }
+
+    @Override
+    public String toString() {
+        return "CallingAppInfo {"
+                + "packageName= " + mPackageName
+                + ", No. of signatures: " + mSignatures.size()
+                + " }";
+    }
+}