chromeos: Refactor toolchain path relativizing into shareable template.

Reduces some copy-pasted code.

Bug: 937821
Change-Id: Ic306e0235de76b43145a58214a95f497e5b2330c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2013906Reviewed-by: George Burgess <gbiv@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734116}

build/toolchain/cros/BUILD.gn

@@ -7,22 +7,38 @@ import("//build/config/sysroot.gni")
 import("//build/toolchain/cros_toolchain.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 
+# This is mostly identical to gcc_toolchain, but handles relativizing toolchain
+# paths. This is needed for CrOS since these paths often change based on the
+# environment. For example, cxx is a relative path picked up on $PATH in the
+# chroot. But in Simple Chrome, cxx is a system-absolute path.
+template("cros_toolchain") {
+  gcc_toolchain(target_name) {
+    forward_variables_from(invoker, "*")
+
+    # Relativize path if compiler is specified such that not to lookup from $PATH
+    # and cc/cxx does not contain additional flags.
+    if (cc != get_path_info(cc, "file") && string_replace(cc, " ", "") == cc) {
+      cc = rebase_path(cc, root_build_dir)
+    }
+    if (cxx != get_path_info(cxx, "file") &&
+        string_replace(cxx, " ", "") == cxx) {
+      cxx = rebase_path(cxx, root_build_dir)
+    }
+    if (ar != get_path_info(ar, "file") && string_replace(ar, " ", "") == ar) {
+      ar = rebase_path(ar, root_build_dir)
+    }
+    if (ld != get_path_info(ld, "file") && string_replace(ld, " ", "") == ld) {
+      ld = rebase_path(ld, root_build_dir)
+    }
+  }
+}
+
 # This is the normal toolchain for most targets.
-gcc_toolchain("target") {
+cros_toolchain("target") {
   ar = cros_target_ar
   cc = cros_target_cc
   cxx = cros_target_cxx
 
-  # Relativize path if compiler is specified such that not to lookup from $PATH
-  # and cc/cxx does not contain additional flags.
-  if (cc != get_path_info(cc, "file") && string_replace(cc, " ", "") == cc) {
-    cc = rebase_path(cc, root_build_dir)
-  }
-  if (cxx != get_path_info(cxx, "file") &&
-      string_replace(cxx, " ", "") == cxx) {
-    cxx = rebase_path(cxx, root_build_dir)
-  }
-
   ld = cxx
   if (cros_target_ld != "") {
     ld = cros_target_ld
@@ -54,20 +70,11 @@ gcc_toolchain("target") {
 # //native_client/src/trusted/service_runtime/linux. It is identical
 # to ":target" except that it forces use_debug_fission, use_gold, and
 # use_sysroot off, and allows the user to set different sets of extra flags.
-gcc_toolchain("nacl_bootstrap") {
+cros_toolchain("nacl_bootstrap") {
   ar = cros_target_ar
   cc = cros_target_cc
   cxx = cros_target_cxx
 
-  # Relativize path if compiler is specified such that not to lookup from $PATH
-  # and cc/cxx does not contain additional flags.
-  if (cc != get_path_info(cc, "file") && string_replace(cc, " ", "") == cc) {
-    cc = rebase_path(cc, root_build_dir)
-  }
-  if (cxx != get_path_info(cxx, "file") &&
-      string_replace(cxx, " ", "") == cxx) {
-    cxx = rebase_path(cxx, root_build_dir)
-  }
   ld = cxx
   if (cros_target_ld != "") {
     ld = cros_target_ld
@@ -95,24 +102,12 @@ gcc_toolchain("nacl_bootstrap") {
   }
 }
 
-gcc_toolchain("host") {
+cros_toolchain("host") {
   # These are args for the template.
   ar = cros_host_ar
   cc = cros_host_cc
   cxx = cros_host_cxx
 
-  # Relativize path if compiler is specified such that not to lookup from $PATH
-  # and cc/cxx does not contain additional flags.
-  if (cc != get_path_info(cc, "file") && string_replace(cc, " ", "") == cc) {
-    cc = rebase_path(cc, root_build_dir)
-  }
-  if (cxx != get_path_info(cxx, "file") &&
-      string_replace(cxx, " ", "") == cxx) {
-    cxx = rebase_path(cxx, root_build_dir)
-  }
-  if (ar != get_path_info(ar, "file") && string_replace(ar, " ", "") == ar) {
-    ar = rebase_path(ar, root_build_dir)
-  }
   ld = cxx
   if (cros_host_ld != "") {
     ld = cros_host_ld
@@ -138,24 +133,12 @@ gcc_toolchain("host") {
   }
 }
 
-gcc_toolchain("v8_snapshot") {
+cros_toolchain("v8_snapshot") {
   # These are args for the template.
   ar = cros_v8_snapshot_ar
   cc = cros_v8_snapshot_cc
   cxx = cros_v8_snapshot_cxx
 
-  # Relativize path if compiler is specified such that not to lookup from $PATH
-  # and cc/cxx does not contain additional flags.
-  if (cc != get_path_info(cc, "file") && string_replace(cc, " ", "") == cc) {
-    cc = rebase_path(cc, root_build_dir)
-  }
-  if (cxx != get_path_info(cxx, "file") &&
-      string_replace(cxx, " ", "") == cxx) {
-    cxx = rebase_path(cxx, root_build_dir)
-  }
-  if (ar != get_path_info(ar, "file") && string_replace(ar, " ", "") == ar) {
-    ar = rebase_path(ar, root_build_dir)
-  }
   ld = cxx
   if (cros_v8_snapshot_ld != "") {
     ld = cros_v8_snapshot_ld