Avoid memcmp on potentially unpacked structs in MailboxManager::TargetNameLess

gpu/command_buffer/service/mailbox_manager.cc

Index: gpu/command_buffer/service/mailbox_manager.cc
diff --git a/gpu/command_buffer/service/mailbox_manager.cc b/gpu/command_buffer/service/mailbox_manager.cc
index 12a13fbac4cea8e77d07779bd44dbe26d9db0f4a..e6962df5ec8ec61c880e8d572f0b39c5c254eafe 100644
--- a/gpu/command_buffer/service/mailbox_manager.cc
+++ b/gpu/command_buffer/service/mailbox_manager.cc
@@ -101,7 +101,9 @@ MailboxManager::TargetName::TargetName(unsigned target, const Mailbox& mailbox)
 
 bool MailboxManager::TargetNameLess(const MailboxManager::TargetName& lhs,
                                     const MailboxManager::TargetName& rhs) {
-  return memcmp(&lhs, &rhs, sizeof(lhs)) < 0;
+  if (lhs.target != rhs.target)
+    return lhs.target < rhs.target;
+  return lhs.mailbox < rhs.mailbox;
 }
 
 }  // namespace gles2