Enable multidex for demos

This is necessary now we have Guava in debug (no-minified) apps.

Also switch to AndroidX multidex to remove the support library dependency.
Temporarily we need to add an Application class, as internal jetification
doesn't seem to handle declaring MultiDexApplication in AndroidManifest.xml.

issue:#7421
PiperOrigin-RevId: 313145023

constants.gradle

@@ -31,6 +31,7 @@ project.ext {
     androidxAppCompatVersion = '1.1.0'
     androidxCollectionVersion = '1.1.0'
     androidxMediaVersion = '1.0.1'
+    androidxMultidexVersion = '2.0.0'
     androidxTestCoreVersion = '1.2.0'
     androidxTestJUnitVersion = '1.1.1'
     androidxTestRunnerVersion = '1.2.0'

demos/cast/build.gradle

@@ -27,6 +27,7 @@ android {
         versionCode project.ext.releaseVersionCode
         minSdkVersion project.ext.minSdkVersion
         targetSdkVersion project.ext.appTargetSdkVersion
+        multiDexEnabled true
     }
 
     buildTypes {
@@ -57,6 +58,7 @@ dependencies {
     implementation project(modulePrefix + 'library-ui')
     implementation project(modulePrefix + 'extension-cast')
     implementation 'androidx.appcompat:appcompat:' + androidxAppCompatVersion
+    implementation 'androidx.multidex:multidex:' + androidxMultidexVersion
     implementation 'androidx.recyclerview:recyclerview:1.1.0'
     implementation 'com.google.android.material:material:1.1.0'
 }

demos/cast/src/main/java/com/google/android/exoplayer2/castdemo/DemoApplication.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2020 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 com.google.android.exoplayer2.castdemo;
+
+import androidx.multidex.MultiDexApplication;
+
+// Note: Multidex is enabled in code not AndroidManifest.xml because the internal build system
+// doesn't dejetify MultiDexApplication in AndroidManifest.xml.
+/** Application for multidex support. */
+public final class DemoApplication extends MultiDexApplication {}

demos/main/build.gradle

@@ -27,6 +27,7 @@ android {
         versionCode project.ext.releaseVersionCode
         minSdkVersion project.ext.minSdkVersion
         targetSdkVersion project.ext.appTargetSdkVersion
+        multiDexEnabled true
     }
 
     buildTypes {
@@ -64,6 +65,7 @@ android {
 dependencies {
     implementation 'androidx.annotation:annotation:' + androidxAnnotationVersion
     implementation 'androidx.appcompat:appcompat:' + androidxAppCompatVersion
+    implementation 'androidx.multidex:multidex:' + androidxMultidexVersion
     implementation 'com.google.android.material:material:1.1.0'
     implementation project(modulePrefix + 'library-core')
     implementation project(modulePrefix + 'library-dash')

demos/main/src/main/java/com/google/android/exoplayer2/demo/DemoApplication.java

@@ -15,7 +15,7 @@
  */
 package com.google.android.exoplayer2.demo;
 
-import android.app.Application;
+import androidx.multidex.MultiDexApplication;
 import com.google.android.exoplayer2.DefaultRenderersFactory;
 import com.google.android.exoplayer2.RenderersFactory;
 import com.google.android.exoplayer2.database.DatabaseProvider;
@@ -40,7 +40,7 @@ import java.io.IOException;
 /**
  * Placeholder application to facilitate overriding Application methods for debugging and testing.
  */
-public class DemoApplication extends Application {
+public class DemoApplication extends MultiDexApplication {
 
   public static final String DOWNLOAD_NOTIFICATION_CHANNEL_ID = "download_channel";
 

extensions/ima/build.gradle

@@ -45,9 +45,9 @@ dependencies {
     implementation 'com.google.android.gms:play-services-ads-identifier:17.0.0'
     compileOnly 'org.jetbrains.kotlin:kotlin-annotations-jvm:' + kotlinAnnotationsVersion
     androidTestImplementation project(modulePrefix + 'testutils')
+    androidTestImplementation 'androidx.multidex:multidex:' + androidxMultidexVersion
     androidTestImplementation 'androidx.test:rules:' + androidxTestRulesVersion
     androidTestImplementation 'androidx.test:runner:' + androidxTestRunnerVersion
-    androidTestImplementation 'com.android.support:multidex:1.0.3'
     androidTestCompileOnly 'org.checkerframework:checker-qual:' + checkerframeworkVersion
     testImplementation project(modulePrefix + 'testutils')
     testImplementation 'com.google.guava:guava:' + guavaVersion