GN: Fix references to $root_build_dir/natives_blob.bin -> $root_out_dir

root_build_dir == root_out_dir in all of these contexts anyways, but
this is more correct.

BUG=

Review URL: https://codereview.chromium.org/1410643013

Cr-Commit-Position: refs/heads/master@{#355725}
diff --git a/content/shell/android/BUILD.gn b/content/shell/android/BUILD.gn
index 6aa4123..4fd3e85 100644
--- a/content/shell/android/BUILD.gn
+++ b/content/shell/android/BUILD.gn
@@ -103,8 +103,8 @@
   }
   if (v8_use_external_startup_data) {
     sources += [
-      "$root_build_dir/natives_blob.bin",
-      "$root_build_dir/snapshot_blob.bin",
+      "$root_out_dir/natives_blob.bin",
+      "$root_out_dir/snapshot_blob.bin",
     ]
     deps += [ "//v8" ]
   }
@@ -159,7 +159,9 @@
     "//base:base_javatests",
     "//net/android:net_javatests",
   ]
-  data_deps = [ ":content_shell_apk" ]
+  data_deps = [
+    ":content_shell_apk",
+  ]
   apk_under_test = ":content_shell_apk"
   apk_name = "ContentShellTest"
   android_manifest = "javatests/AndroidManifest.xml"