Fix SandboxMacTest.RendererCannotWriteHomeDir on macOS 10.10

Tbr: kerrnel@chromium.org
Bug: 902597
Change-Id: I2b18b5b95d3a769e1185559afdcc81d25da5551f
Reviewed-on: https://chromium-review.googlesource.com/c/1331227Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607132}

content/browser/sandbox_mac_unittest.mm

@@ -26,7 +26,7 @@ namespace {
 // crbug.com/740009: This allows the unit test to cleanup temporary directories,
 // and is safe since this is only a unit test.
 constexpr char kTempDirSuffix[] =
-    "(allow file* (subpath \"/private/var/folders/\"))";
+    "(allow file* (subpath \"/private/var/folders\"))";
 
 class SandboxMacTest : public base::MultiProcessTest {
  protected: