Fix open source Firestore Android for building the testapp with

Couple of issues came up when building the testapp: the Firestore source directory variable wasn't being set in that case, and it was unnecessarily trying to build the Core Firestore for Android.

PiperOrigin-RevId: 300421911

Author: a-maurice

CMakeLists.txt

@@ -127,11 +127,12 @@ else()
   message(STATUS "Downloading external project dependencies...")
   download_external_sources()
   message(STATUS "Download complete.")
+
+  set(FIRESTORE_SOURCE_DIR ${FIREBASE_BINARY_DIR}/external/src/firestore)
 endif()
 
 # Include Firestore's external build early to resolve conflicts on packages.
 if(NOT ANDROID AND FIREBASE_INCLUDE_FIRESTORE)
-  set(FIRESTORE_SOURCE_DIR ${FIREBASE_BINARY_DIR}/external/src/firestore)
   set(FIRESTORE_BINARY_DIR ${FIRESTORE_SOURCE_DIR}-build)
 
   set(

cmake/external_rules.cmake

@@ -37,20 +37,9 @@ function(download_external_sources)
     set(external_platform DESKTOP)
   endif()
 
-  # Prepare the Firestore CMake build as well.
+  # When building with Firestore, use the NanoPB source from that instead.
   if(FIREBASE_INCLUDE_FIRESTORE)
     set(FIRESTORE_BINARY_DIR ${PROJECT_BINARY_DIR}/external/src/firestore-build)
-
-    execute_process(
-      COMMAND
-        ${ENV_COMMAND} cmake
-        -DFIREBASE_DOWNLOAD_DIR=${FIREBASE_DOWNLOAD_DIR}
-        -DCMAKE_INSTALL_PREFIX=${FIREBASE_INSTALL_DIR}
-        ${PROJECT_BINARY_DIR}/external/src/firestore
-
-      WORKING_DIRECTORY ${FIRESTORE_BINARY_DIR}
-    )
-
     set(NANOPB_SOURCE_DIR ${FIRESTORE_BINARY_DIR}/external/src/nanopb)
   endif()