mac: Expose keychain access frequency to Telemetry.

components/os_crypt/os_crypt_mac.mm

Index: components/os_crypt/os_crypt_mac.mm
diff --git a/components/os_crypt/os_crypt_mac.mm b/components/os_crypt/os_crypt_mac.mm
index 507993196aeefde7c018114ef0e4951c9ed810d3..dcfd2fbca12a7996add2ba1009753e1270b55036 100644
--- a/components/os_crypt/os_crypt_mac.mm
+++ b/components/os_crypt/os_crypt_mac.mm
@@ -16,6 +16,7 @@
 #include "components/os_crypt/os_crypt_switches.h"
 #include "crypto/apple_keychain.h"
 #include "crypto/encryptor.h"
+#include "crypto/mock_apple_keychain.h"
 #include "crypto/symmetric_key.h"
 
 using crypto::AppleKeychain;
@@ -57,7 +58,8 @@ crypto::SymmetricKey* GetEncryptionKey() {
 
   std::string password;
   if (use_mock_keychain || mock_keychain_command_line_flag) {
-    password = "mock_password";
+    crypto::MockAppleKeychain keychain;
+    password = keychain.GetEncryptionPassword();
   } else {
     AppleKeychain keychain;
     KeychainPassword encryptor_password(keychain);