zygote: Don't CHECK if browser gone during zygote startup

content/common/sandbox_linux/sandbox_linux.cc

Index: content/common/sandbox_linux/sandbox_linux.cc
diff --git a/content/common/sandbox_linux/sandbox_linux.cc b/content/common/sandbox_linux/sandbox_linux.cc
index c45d826b9e86b92ea821d87dc9899a7d56304383..d605404eda088e2c914310924859db22ffeccdf8 100644
--- a/content/common/sandbox_linux/sandbox_linux.cc
+++ b/content/common/sandbox_linux/sandbox_linux.cc
@@ -110,6 +110,7 @@ LinuxSandbox::LinuxSandbox()
       seccomp_bpf_with_tsync_supported_(false),
       yama_is_enforcing_(false),
       initialize_sandbox_ran_(false),
+      exiting_before_initialize_sandbox_(false),
       setuid_sandbox_client_(sandbox::SetuidSandboxClient::Create()) {
   if (setuid_sandbox_client_ == NULL) {
     LOG(FATAL) << "Failed to instantiate the setuid sandbox client.";
@@ -121,7 +122,7 @@ LinuxSandbox::LinuxSandbox()
 }
 
 LinuxSandbox::~LinuxSandbox() {
-  if (pre_initialized_) {
+  if (pre_initialized_ && !exiting_before_initialize_sandbox_) {
     CHECK(initialize_sandbox_ran_);
   }
 }