crypto: Enable overriding NSS DB location.

crypto/nss_util.cc

Index: crypto/nss_util.cc
diff --git a/crypto/nss_util.cc b/crypto/nss_util.cc
index 359f78fb87a89b172245fb6f127344547efb5dc0..4d97bbf99d597ea9e949691fd0a08ede48c398c8 100644
--- a/crypto/nss_util.cc
+++ b/crypto/nss_util.cc
@@ -89,12 +89,22 @@ std::string GetNSSErrorMessage() {
 #if !defined(OS_CHROMEOS)
 base::FilePath GetDefaultConfigDirectory() {
   base::FilePath dir;
-  PathService::Get(base::DIR_HOME, &dir);
-  if (dir.empty()) {
-    LOG(ERROR) << "Failed to get home directory.";
-    return dir;
+
+  std::unique_ptr<base::Environment> env(base::Environment::Create());
+  static const char kUseCacheEnvVar[] = "NSS_DEFAULT_DB_DIR";
+  std::string default_db_file;
+  if (env->GetVar(kUseCacheEnvVar, &default_db_file) &&
+      default_db_file.length() > 0) {
+    dir = base::FilePath(default_db_file);
+  } else {
+    PathService::Get(base::DIR_HOME, &dir);
+    if (dir.empty()) {
+      LOG(ERROR) << "Failed to get home directory.";
+      return dir;
+    }
+    dir = dir.AppendASCII(".pki").AppendASCII("nssdb");
   }
-  dir = dir.AppendASCII(".pki").AppendASCII("nssdb");
+
   if (!base::CreateDirectory(dir)) {
     LOG(ERROR) << "Failed to create " << dir.value() << " directory.";
     dir.clear();