Migrate ExperimentPayload to AB Testing (#563)

* Migrate ExperimentPayload to AB Testing

* Add issue link.

* Export proto definition.

Author: allisonbm92

firebase-abt/firebase-abt.gradle

@@ -14,26 +14,50 @@
 
 plugins {
     id 'firebase-library'
+    id 'com.google.protobuf'
 }
 
 firebaseLibrary {
     testLab.enabled = false
     publishSources = true
 }
 
+// TODO(issue/568): Remove this once legacy logic is removed from Remote Config.
+protobuf {
+    protoc {
+        artifact = 'com.google.protobuf:protoc:3.4.0'
+    }
+    plugins {
+        javalite {
+            artifact = 'com.google.protobuf:protoc-gen-javalite:3.0.0'
+        }
+    }
+    generateProtoTasks {
+        all().each { task ->
+            task.builtins {
+                remove java
+            }
+            task.plugins {
+                javalite {}
+            }
+        }
+    }
+}
+
 android {
 
     lintOptions {
         abortOnError false
     }
     sourceSets {
         main {
-            java {
-            }
-        }
-        test {
-            java {
+            proto {
+                srcDir 'src/proto'
             }
+
+	    resources {
+	        srcDir 'src/proto/com/google/protos'
+	    }
         }
     }
 
@@ -61,6 +85,7 @@ dependencies {
     implementation ('com.google.firebase:firebase-measurement-connector:18.0.0') {
         exclude group: "com.google.firebase", module: "firebase-common"
     }
+    implementation 'com.google.protobuf:protobuf-lite:3.0.1'
     testImplementation 'org.mockito:mockito-core:2.25.0'
     testImplementation 'com.google.truth:truth:0.44'
     testImplementation 'junit:junit:4.13-beta-2'

firebase-config/src/proto/com/google/protos/developers/mobile/abt/proto/experiment_payload.proto renamed to firebase-abt/src/proto/com/google/protos/developers/mobile/abt/proto/experiment_payload.proto

@@ -50,11 +50,6 @@ protobuf {
     }
 }
 
-firebaseLibrary {
-    testLab.enabled = true
-    publishSources = true
-}
-
 android {
     compileSdkVersion project.targetSdkVersion
     defaultConfig {