[Chromecast] Add /system/chrome to the rpath for component builds.

build/config/chromecast/BUILD.gn

Index: build/config/chromecast/BUILD.gn
diff --git a/build/config/chromecast/BUILD.gn b/build/config/chromecast/BUILD.gn
index 6c208a1b7acfb214a9310d9345bd25e48b2669b3..811582f162f37311f93b68ccdd08129822f65a7b 100644
--- a/build/config/chromecast/BUILD.gn
+++ b/build/config/chromecast/BUILD.gn
@@ -37,6 +37,13 @@ config("ldconfig") {
     "-Wl,-rpath=\$ORIGIN/lib",
     "-Wl,-rpath=\$ORIGIN",
   ]
+
+  # Binaries which don't live in the same directory as Chrome component
+  # libraries may still depend on them. Explicitly add the component library
+  # directory to the rpath for the component build.
+  if (is_component_build) {
+    ldflags += [ "-Wl,-rpath=/system/chrome" ]
+  }
 }
 
 config("executable_config") {