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

content/gpu/gpu_main.cc

Index: content/gpu/gpu_main.cc
diff --git a/content/gpu/gpu_main.cc b/content/gpu/gpu_main.cc
index 7cfd446cb9219de3421523c0df760dbffb8c155b..f90858fcdeb8b3567be6b7eda37d396f8e4e4d47 100644
--- a/content/gpu/gpu_main.cc
+++ b/content/gpu/gpu_main.cc
@@ -450,9 +450,13 @@ bool StartSandboxLinux(const gpu::GPUInfo& gpu_info,
   }
 
 #if defined(ADDRESS_SANITIZER)
+  std::stringstream ss;
+  ss << "gpu." << base::RandUint64();
+  std::string sancov_file_name = ss.str();

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

please do:

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

instead.

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

Done.

   LinuxSandbox* linux_sandbox = LinuxSandbox::GetInstance();
   linux_sandbox->sanitizer_args()->coverage_sandboxed = 1;
-  linux_sandbox->sanitizer_args()->coverage_fd = -1;
+  linux_sandbox->sanitizer_args()->coverage_fd =
+      __sanitizer_maybe_open_cov_file(sancov_file_name.c_str());
   linux_sandbox->sanitizer_args()->coverage_max_block_size = 0;
 #endif