linux: expose the ProcessSingleton timeout to speed tests

chrome/browser/process_singleton.h

Index: chrome/browser/process_singleton.h
diff --git a/chrome/browser/process_singleton.h b/chrome/browser/process_singleton.h
index 122618f386a86cbc4a64f4aa4d029fe4168ef722..e06a7e8da65282f5be94ea8ef86402c7da1b7612 100644
--- a/chrome/browser/process_singleton.h
+++ b/chrome/browser/process_singleton.h
@@ -40,6 +40,7 @@ class ProcessSingleton : public NonThreadSafe {
   explicit ProcessSingleton(const FilePath& user_data_dir);
   ~ProcessSingleton();
 
+  // Notify another process, if available.
   // Returns true if another process was found and notified, false if we
   // should continue with this process.
   // Windows code roughly based on Mozilla.
@@ -49,6 +50,12 @@ class ProcessSingleton : public NonThreadSafe {
   // first one, so this function won't find it.
   NotifyResult NotifyOtherProcess();
 
+#if defined(OS_LINUX)
+  // Exposed for testing.  We use a timeout on Linux, and in tests we want
+  // this timeout to be short.
+  NotifyResult NotifyOtherProcessWithTimeout(int timeout_seconds);
+#endif
+
   // Sets ourself up as the singleton instance.
   void Create();