TurboModule Android: compile codegen C++ output into librntester_appmodules.so

Summary:
The react-native-codegen provides Android.mk in the Android C++ output, but for RNTester (or hosting apps), we should just compile the codegen output with the rest of the app-specific C++ files. This is to simplify the build configuration, and also to not add too many additional .so libs to the APK.

With this commit, `RNTesterAppModuleProvider.cpp` should be "complete" for RNTester use-case. This TurboModule lookup function is the one described in react-native-community/discussions-and-proposals#273.

Changelog: [Internal]

Reviewed By: hramos

Differential Revision: D23913149

fbshipit-source-id: d1ca136787b87a0e8e6504318e1f0a78efef46ea

Author: fkgozali

packages/rn-tester/android/app/build.gradle

@@ -198,6 +198,7 @@ if (enableCodegen) {
                             "NDK_TOOLCHAIN_VERSION=clang",
                             // The following paths assume building React Native from source.
                             // TODO: Find a better way without pointing to ReactAndroid/build dir.
+                            "GENERATED_SRC_DIR=$buildDir/generated/source",
                             "REACT_ANDROID_SRC_DIR=$reactAndroidProjectDir/src/main",
                             "REACT_COMMON_DIR=$rootDir/ReactCommon",
                             "REACT_GENERATED_SRC_DIR=$reactAndroidBuildDir/generated/source",

packages/rn-tester/android/app/src/main/jni/Android.mk

@@ -60,9 +60,10 @@ include $(PREBUILT_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := rntester_appmodules
-LOCAL_C_INCLUDES := $(LOCAL_PATH)
-LOCAL_SRC_FILES := $(wildcard $(LOCAL_PATH)/*.cpp)
-LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
+# Note: Build the react-native-codegen output along with other app-specific C++ files.
+LOCAL_C_INCLUDES := $(LOCAL_PATH) $(GENERATED_SRC_DIR)/codegen/jni
+LOCAL_SRC_FILES := $(wildcard $(LOCAL_PATH)/*.cpp) $(wildcard $(GENERATED_SRC_DIR)/codegen/jni/*.cpp)
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH) $(GENERATED_SRC_DIR)/codegen/jni
 LOCAL_SHARED_LIBRARIES := libreact_nativemodule_core libreact_nativemodule_manager libreact_codegen_reactandroidspec
 LOCAL_CFLAGS := \
   -DLOG_TAG=\"ReactNative\"

packages/rn-tester/android/app/src/main/jni/RNTesterAppModuleProvider.cpp

@@ -7,12 +7,17 @@
 
 #include "RNTesterAppModuleProvider.h"
 
+#include <PackagesRnTesterAndroidAppSpec.h>
 #include <ReactAndroidSpec.h>
 
 namespace facebook {
 namespace react {
 
 std::shared_ptr<TurboModule> RNTesterAppModuleProvider(const std::string moduleName, const JavaTurboModule::InitParams &params) {
+  auto module = PackagesRnTesterAndroidAppSpec_ModuleProvider(moduleName, params);
+  if (module != nullptr) {
+    return module;
+  }
   return ReactAndroidSpec_ModuleProvider(moduleName, params);
 }