Define magic descriptors in one place.

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 1f0e9f5fb52de28caafcfd8007bf7267e2d70376..6fe2d1e1f2b6d1b46ac2930abe1031050ce4f616 100644
--- a/content/zygote/zygote_main_linux.cc
+++ b/content/zygote/zygote_main_linux.cc
@@ -69,7 +69,7 @@ static void ProxyLocaltimeCallToBrowser(time_t input, struct tm* output,
 
   uint8_t reply_buf[512];
   const ssize_t r = UnixDomainSocket::SendRecvMsg(
-      Zygote::kMagicSandboxIPCDescriptor, reply_buf, sizeof(reply_buf), NULL,
+      kMagicSandboxIPCDescriptor, reply_buf, sizeof(reply_buf), NULL,
       request);
   if (r == -1) {
     memset(output, 0, sizeof(struct tm));
@@ -393,7 +393,7 @@ static bool EnterSandbox(sandbox::SetuidSandboxClient* setuid_sandbox,
 
   PreSandboxInit();
   SkFontConfigInterface::SetGlobal(
-      new FontConfigIPC(Zygote::kMagicSandboxIPCDescriptor))->unref();
+      new FontConfigIPC(kMagicSandboxIPCDescriptor))->unref();
 
   if (setuid_sandbox->IsSuidSandboxChild()) {
     // Use the SUID sandbox.  This still allows the seccomp sandbox to
@@ -466,7 +466,7 @@ bool ZygoteMain(const MainFunctionParams& params,
 
   if (forkdelegate != NULL) {
     VLOG(1) << "ZygoteMain: initializing fork delegate";
-    forkdelegate->Init(Zygote::kMagicSandboxIPCDescriptor);
+    forkdelegate->Init(kMagicSandboxIPCDescriptor);
   } else {
     VLOG(1) << "ZygoteMain: fork delegate is NULL";
   }