Use a single, generic, global zygote to temporarily resolve perf regressions.

content/public/browser/zygote_handle_linux.h

Index: content/public/browser/zygote_handle_linux.h
diff --git a/content/public/browser/zygote_handle_linux.h b/content/public/browser/zygote_handle_linux.h
index b644c514b60775ae4c1c03cb73b3e15a53e5e315..6419b7475b697bd692b6d2b1f8be86af40cbcb71 100644
--- a/content/public/browser/zygote_handle_linux.h
+++ b/content/public/browser/zygote_handle_linux.h
@@ -5,8 +5,6 @@
 #ifndef CONTENT_PUBLIC_BROWSER_ZYGOTE_HANDLE_LINUX_H_
 #define CONTENT_PUBLIC_BROWSER_ZYGOTE_HANDLE_LINUX_H_
 
-#include <cstddef>
-
 #include "content/common/content_export.h"
 #include "content/public/common/zygote_handle.h"
 
@@ -16,6 +14,11 @@ namespace content {
 // ZygoteHandle used to communicate with it.
 CONTENT_EXPORT ZygoteHandle CreateZygote();
 
+// Returns a handle to a global generic zygote object. This function allows the
+// browser to launch and use a single zygote process until the performance
+// issues around launching multiple zygotes are resolved.
+CONTENT_EXPORT ZygoteHandle* GetGenericZygote();
+
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_ZYGOTE_HANDLE_LINUX_H_