Add gcc_target_rpath gn arg

build/config/gcc/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/sysroot.gni")
 import("//build/toolchain/toolchain.gni")
 
+declare_args() {
+  # When non empty, overrides the target rpath value. This allows a user to
+  # make a Chromium build where binaries and shared libraries are meant to be
+  # installed into separate directories, like /usr/bin/chromium and
+  # /usr/lib/chromium for instance. It is useful when a build system that
+  # generates a whole target root filesystem (like Yocto) is used on top of gn,
+  # especially when cross-compiling.
+  # Note: this gn arg is similar to gyp target_rpath generator flag.
+  gcc_target_rpath = ""
+}
+
 # This config causes functions not to be automatically exported from shared
 # libraries. By default, all symbols are exported but this means there are
 # lots of exports that slow everything down. In general we explicitly mark
 # which functiosn we want to export from components.
 #
 # Some third_party code assumes all functions are exported so this is separated
 # into its own config so such libraries can remove this config to make symbols
 # public again.
 #
 # See http://gcc.gnu.org/wiki/Visibility
@@ skipping 34 matching lines @@
 #    configs += [ "//build/config/gcc:rpath_for_built_shared_libraries" ]
 #  }
 config("rpath_for_built_shared_libraries") {
   if (!is_android) {
     # Note: Android doesn't support rpath.
     if (shlib_subdir != ".") {
       rpath_link = "${shlib_subdir}/"
     } else {
       rpath_link = "."
     }
-    ldflags = [
-      # Want to pass "\$". GN will re-escape as required for ninja.
-      "-Wl,-rpath=\$ORIGIN/${rpath_link}",
-      "-Wl,-rpath-link=${rpath_link}",
-    ]
+    if (current_toolchain != default_toolchain || gcc_target_rpath == "") {
+      ldflags = [
+        # Want to pass "\$". GN will re-escape as required for ninja.
+        "-Wl,-rpath=\$ORIGIN/${rpath_link}",
+        "-Wl,-rpath-link=${rpath_link}",
+      ]
+    } else {
+      ldflags = [
+        "-Wl,-rpath=${gcc_target_rpath}",
+        "-Wl,-rpath-link=${rpath_link}",
+      ]
+    }
   }
 }
 
 # Settings for executables.
 config("executable_ldconfig") {
   # WARNING! //sandbox/linux:chrome_sandbox will not pick up this
   # config, because it is a setuid binary that needs special flags.
   # If you add things to this config, make sure you check to see
   # if they should be added to that target as well.
   ldflags = []
@@ skipping 35 matching lines @@
       # and the new DT_RUNPATH doesn't work without --no-as-needed flag.
       "-Wl,--disable-new-dtags",
     ]
   }
 }
 
 config("no_exceptions") {
   cflags_cc = [ "-fno-exceptions" ]
   cflags_objcc = cflags_cc
 }