floss: have floss built with libstructuredmetrics

Update the Floss build process to utilize the new GN flag target_os and
environmental variable TARGET_OS_VARIENT to include
libstructuredmetrics when building for ChromeOS. Correct GN syntaxes.

BUG: 232098615
Tag: #floss
Test: ./build.py --target test
Test: emerge-${BOARD} floss

Change-Id: I0bf960751643f12f7e1ef03c7aa844d112fbb5d5

BUILD.gn

@@ -25,7 +25,7 @@ group("all") {
 }
 
 # Tools should be built for the host target.
-if (host_cpu == target_cpu && host_os == target_os) {
+if (target_os == "linux") {
   group("tools") {
     deps = [ "//bt/system:tools" ]
   }

system/BUILD.gn

@@ -103,12 +103,15 @@ config("target_defaults") {
     "-Wno-unknown-warning-option",
     "-Wno-final-dtor-non-final-class",
 
-    string_join("", ["-ffile-prefix-map=", rebase_path(".", "${root_build_dir}", "."), "/= "])
+    string_join("",
+                [
+                  "-ffile-prefix-map=",
+                  rebase_path(".", "${root_build_dir}", "."),
+                  "/= ",
+                ]),
   ]
 
-  cflags_cc = [
-    "-std=c++17",
-  ]
+  cflags_cc = [ "-std=c++17" ]
 
   defines = [
     "HAS_NO_BDROID_BUILDCFG",
@@ -117,7 +120,7 @@ config("target_defaults") {
     "TARGET_FLOSS",
     "EXPORT_SYMBOL=__attribute__((visibility(\"default\")))",
     "FALLTHROUGH_INTENDED=[[clang::fallthrough]]",
-    "BTIF_HF_FEATURES=0x00000640"
+    "BTIF_HF_FEATURES=0x00000640",
   ]
 
   if (!(defined(use.bt_nonstandard_codecs) && use.bt_nonstandard_codecs)) {
@@ -125,6 +128,10 @@ config("target_defaults") {
   }
 
   configs = [ ":external_libchrome" ]
+
+  if (target_os == "chromeos") {
+    configs += [ ":external_chromeos" ]
+  }
 }
 
 group("libbt-platform-protos-lite") {
@@ -223,3 +230,14 @@ if (defined(use.bt_nonstandard_codecs) && use.bt_nonstandard_codecs) {
     pkg_deps = [ "ldacBT-abr" ]
   }
 }
+
+# To include ChroemOS-specific libraries and build dependencies.
+if (target_os == "chromeos") {
+  config("external_chromeos") {
+    configs = [ ":pkgpkg_libstructuredmetrics" ]
+  }
+
+  pkg_config("pkgpkg_libstructuredmetrics") {
+    pkg_deps = [ "libstructuredmetrics" ]
+  }
+}

system/gd/rust/linux/service/build.rs

@@ -26,5 +26,10 @@ fn main() {
     Config::new().probe("libmodp_b64").unwrap();
     Config::new().probe("tinyxml2").unwrap();
 
+    // Include ChromeOS-specific dependencies.
+    if option_env!("TARGET_OS_VARIANT").unwrap_or("None").to_string() == "chromeos" {
+        Config::new().probe("libstructuredmetrics").unwrap();
+    }
+
     println!("cargo:rerun-if-changed=build.rs");
 }