OSCrypt for POSIX uses libsecret to store a randomised encryption key.

components/os_crypt/os_crypt_unittest.cc

Index: components/os_crypt/os_crypt_unittest.cc
diff --git a/components/os_crypt/os_crypt_unittest.cc b/components/os_crypt/os_crypt_unittest.cc
index 9837cbc29a0d8d1725056fdd79006e3e9e54e2ed..2f00f436765059014ee04bdf4807b7a6349e2c8d 100644
--- a/components/os_crypt/os_crypt_unittest.cc
+++ b/components/os_crypt/os_crypt_unittest.cc
@@ -11,6 +11,7 @@
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
+#include "components/os_crypt/key_storage_mock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
@@ -19,16 +20,41 @@ class OSCryptTest : public testing::Test {
  public:
   OSCryptTest() {}
 
-  void SetUp() override {
 #if defined(OS_MACOSX)
-    OSCrypt::UseMockKeychain(true);
+  void SetUp() override { OSCrypt::UseMockKeychain(true); }

[Lei Zhang, 2016/05/19 22:45:38]

I'd highly prefer not to have two different implementations of the same
function. Can we keep the ifdefs inside the function, like before?

[cfroussios, 2016/05/20 16:44:52]

Done.

 #endif
+
+#if defined(USE_LIBSECRET)
+  void SetUp() override {
+    key_storage_static_ = &key_storage_;
+    UseMockKeyStorageForTesting(true, &GetKeyStorage, &GetPassword);
   }
 
+  void TearDown() override {
+    key_storage_static_ = nullptr;
+    UseMockKeyStorageForTesting(false, nullptr, nullptr);
+  }
+
+ protected:
+  KeyStorageMock key_storage_;
+
+ private:
+  // Needed, so that we can return our |key_storage_| through static methods
+  static KeyStorageMock* key_storage_static_;

[Lei Zhang, 2016/05/19 22:45:38]

Many places use s_foo_ here, like g_foo for globals.

[cfroussios, 2016/05/20 16:44:52]

Done.

+
+  static KeyStorageLinux* GetKeyStorage() { return key_storage_static_; }
+
+  static std::string* GetPassword() { return key_storage_static_->GetKeyPtr(); }
+#endif
+
  private:
   DISALLOW_COPY_AND_ASSIGN(OSCryptTest);
 };
 
+#if defined(USE_LIBSECRET)
+KeyStorageMock* OSCryptTest::key_storage_static_ = nullptr;
+#endif
+
 TEST_F(OSCryptTest, String16EncryptionDecryption) {
   base::string16 plaintext;
   base::string16 result;