[Chromecast][GN] Update Chromecast default rpath.

build/config/chromecast/BUILD.gn

 # Copyright 2015 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/chromecast_build.gni")
 
 assert(is_chromecast)
 
 config("static_config") {
   ldflags = [
     # We want to statically link libstdc++/libgcc.
     "-static-libstdc++",
     "-static-libgcc",
 
     # Don't allow visible symbols from libraries that contain
     # assembly code with symbols that aren't hidden properly.
     # http://b/26390825
     "-Wl,--exclude-libs=libffmpeg.a",
   ]
 }
 
 config("ldconfig") {
   visibility = [ ":*" ]
 
-  # Chromecast executables depend on several shared libraries in $ORIGIN. Add
-  # $ORIGIN to the rpath of these executables. This is not inherited by default
-  # when depending on these targets for security reasons (see comments in
-  # //build/config/gcc/BUILD.gn)
-  configs = [ "//build/config/gcc:rpath_for_built_shared_libraries" ]
+  # Chromecast executables depend on several shared libraries in
+  # /oem_cast_shlib, $ORIGIN, and $ORIGIN/lib. Add these rpaths to each binary.
+  # This is explicitly disabled in Chrome for security reasons (see comments in
+  # //build/config/gcc/BUILD.gn), but necessary on Chromecast so that OEM's may
+  # override the default libraries shipped in the Cast receiver package.
+  ldflags = [
+    "-Wl,-rpath=/oem_cast_shlib",
+    "-Wl,-rpath=\$ORIGIN/lib",
+    "-Wl,-rpath=\$ORIGIN",
+  ]
 }
 
 config("executable_config") {
   configs = [ ":ldconfig" ]
 
   if (current_cpu == "arm") {
     ldflags = [
       # Export stdlibc++ and libgcc symbols to force shlibs to refer to these
       # symbols from the executable.
       "-Wl,--export-dynamic",
@@ skipping 15 matching lines @@
     configs += [ ":static_config" ]
   }
 }
 
 config("shared_library_config") {
   configs = [ ":ldconfig" ]
   if (current_cpu == "arm") {
     configs += [ ":static_config" ]
   }
 }