Update the new app template to use CMake instead of Android.mk (#34354)

Summary:
Pull Request resolved: #34354

This change simplifies the setup for New Architecture for users on Android.
Instead of using the Android.mk file, users can now use a CMake file which
encapsulate a lot of the complexities and reduces the maintainance cost.

Android.mk support is kept for backward compatibility.

Changelog:
[Android] [Changed] - Update the new app template to use CMake instead of Android.mk

Reviewed By: cipolleschi

Differential Revision: D38460536

fbshipit-source-id: 244dbd3936c3ff238905bcb2b2c9e91a008af8bc

template/android/app/build.gradle

@@ -143,26 +143,14 @@ android {
         buildConfigField "boolean", "IS_NEW_ARCHITECTURE_ENABLED", isNewArchitectureEnabled().toString()
 
         if (isNewArchitectureEnabled()) {
-            // We configure the NDK build only if you decide to opt-in for the New Architecture.
+            // We configure the CMake build only if you decide to opt-in for the New Architecture.
             externalNativeBuild {
-                ndkBuild {
-                    arguments "APP_PLATFORM=android-21",
-                        "APP_STL=c++_shared",
-                        "NDK_TOOLCHAIN_VERSION=clang",
-                        "GENERATED_SRC_DIR=$buildDir/generated/source",
-                        "PROJECT_BUILD_DIR=$buildDir",
-                        "REACT_ANDROID_DIR=$rootDir/../node_modules/react-native/ReactAndroid",
-                        "REACT_ANDROID_BUILD_DIR=$rootDir/../node_modules/react-native/ReactAndroid/build",
-                        "NODE_MODULES_DIR=$rootDir/../node_modules"
-                    cFlags "-Wall", "-Werror", "-fexceptions", "-frtti", "-DWITH_INSPECTOR=1"
-                    cppFlags "-std=c++17"
-                    // Make sure this target name is the same you specify inside the
-                    // src/main/jni/Android.mk file for the `LOCAL_MODULE` variable.
-                    targets "helloworld_appmodules"
-                    // Fix for windows limit on number of character in file paths and in command lines
-                    if (Os.isFamily(Os.FAMILY_WINDOWS)) {
-                        arguments "NDK_APP_SHORT_COMMANDS=true"
-                    }
+                cmake {
+                    arguments "-DPROJECT_BUILD_DIR=$buildDir",
+                        "-DREACT_ANDROID_DIR=$rootDir/../node_modules/react-native/ReactAndroid",
+                        "-DREACT_ANDROID_BUILD_DIR=$rootDir/../node_modules/react-native/ReactAndroid/build",
+                        "-DNODE_MODULES_DIR=$rootDir/../node_modules",
+                        "-DANDROID_STL=c++_shared"
                 }
             }
             if (!enableSeparateBuildPerCPUArchitecture) {
@@ -176,8 +164,8 @@ android {
     if (isNewArchitectureEnabled()) {
         // We configure the NDK build only if you decide to opt-in for the New Architecture.
         externalNativeBuild {
-            ndkBuild {
-                path "$projectDir/src/main/jni/Android.mk"
+            cmake {
+                path "$projectDir/src/main/jni/CMakeLists.txt"
             }
         }
         def reactAndroidProjectDir = project(':ReactAndroid').projectDir
@@ -199,15 +187,15 @@ android {
             preReleaseBuild.dependsOn(packageReactNdkReleaseLibs)
 
             // Due to a bug inside AGP, we have to explicitly set a dependency
-            // between configureNdkBuild* tasks and the preBuild tasks.
+            // between configureCMakeDebug* tasks and the preBuild tasks.
             // This can be removed once this is solved: https://issuetracker.google.com/issues/207403732
-            configureNdkBuildRelease.dependsOn(preReleaseBuild)
-            configureNdkBuildDebug.dependsOn(preDebugBuild)
+            configureCMakeRelWithDebInfo.dependsOn(preReleaseBuild)
+            configureCMakeDebug.dependsOn(preDebugBuild)
             reactNativeArchitectures().each { architecture ->
-                tasks.findByName("configureNdkBuildDebug[${architecture}]")?.configure {
+                tasks.findByName("configureCMakeDebug[${architecture}]")?.configure {
                     dependsOn("preDebugBuild")
                 }
-                tasks.findByName("configureNdkBuildRelease[${architecture}]")?.configure {
+                tasks.findByName("configureCMakeRelWithDebInfo[${architecture}]")?.configure {
                     dependsOn("preReleaseBuild")
                 }
             }

template/android/app/src/main/jni/CMakeLists.txt

@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 3.13)
+
+# Define the library name here.
+project(rntester_appmodules)
+
+# This file includes all the necessary to let you build your application with the New Architecture.
+include(${REACT_ANDROID_DIR}/cmake-utils/ReactNative-application.cmake)