AsanCoverage: make the filenames of zygote/gpu coverage files more unique.

content/zygote/zygote_main_linux.cc

Index: content/zygote/zygote_main_linux.cc
diff --git a/content/zygote/zygote_main_linux.cc b/content/zygote/zygote_main_linux.cc
index bae86093614b70e88be396ff75da7394b04069f5..e528d2c719d27357f89e838df235a5215110332d 100644
--- a/content/zygote/zygote_main_linux.cc
+++ b/content/zygote/zygote_main_linux.cc
@@ -496,7 +496,11 @@ bool ZygoteMain(const MainFunctionParams& params,
   LinuxSandbox* linux_sandbox = LinuxSandbox::GetInstance();
 
 #if defined(ADDRESS_SANITIZER)
-  base::ScopedFD sancov_file_fd(__sanitizer_maybe_open_cov_file("zygote"));
+  std::stringstream ss;

[jln (very slow on Chromium), 2014/06/03 21:43:40]

please do:

const std::string sancov_file_name = "zygote." +
base::Uint64ToString(base::RandUint64());

instead.

[earthdok, 2014/06/03 21:49:27]

Done.

+  ss << "zygote." << base::RandUint64();
+  std::string sancov_file_name = ss.str();
+  base::ScopedFD sancov_file_fd(
+      __sanitizer_maybe_open_cov_file(sancov_file_name.c_str()));
   int sancov_socket_fds[2] = {-1, -1};
   CreateSanitizerCoverageSocketPair(sancov_socket_fds);
   linux_sandbox->sanitizer_args()->coverage_sandboxed = 1;