[Android] Allow __NR_rt_tgsigqueueinfo under seccomp.

content/common/sandbox_linux/android/sandbox_bpf_base_policy_android.cc

Index: content/common/sandbox_linux/android/sandbox_bpf_base_policy_android.cc
diff --git a/content/common/sandbox_linux/android/sandbox_bpf_base_policy_android.cc b/content/common/sandbox_linux/android/sandbox_bpf_base_policy_android.cc
index 4cd502d8487729950a891e6fc610a0bb946c35c5..a2384c9c440c54dbdaa6b12a78fd88decea23034 100644
--- a/content/common/sandbox_linux/android/sandbox_bpf_base_policy_android.cc
+++ b/content/common/sandbox_linux/android/sandbox_bpf_base_policy_android.cc
@@ -50,7 +50,8 @@ BoolExpr RestrictSocketArguments(const Arg<int>& domain,
 }  // namespace
 
 SandboxBPFBasePolicyAndroid::SandboxBPFBasePolicyAndroid()
-    : SandboxBPFBasePolicy() {}
+    : SandboxBPFBasePolicy(),
+      pid_(getpid()) {}
 
 SandboxBPFBasePolicyAndroid::~SandboxBPFBasePolicyAndroid() {}
 
@@ -122,6 +123,13 @@ ResultExpr SandboxBPFBasePolicyAndroid::EvaluateSyscall(int sysno) const {
       break;
   }
 
+  // https://crbug.com/644759
+  if (sysno == __NR_rt_tgsigqueueinfo) {
+    const Arg<pid_t> tgid(0);
+    return If(tgid == pid_, Allow())
+           .Else(Error(EPERM));
+  }
+
 #if defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) || \
       defined(__mips__)
   if (sysno == __NR_socket) {