Revert of Multiprocess test client: Android child process launcher rework.

base/posix/global_descriptors.h

Index: base/posix/global_descriptors.h
diff --git a/base/posix/global_descriptors.h b/base/posix/global_descriptors.h
index 30db2b7ab729cb7838aff873e0982345f1b8736f..edb299de5c957cc36f5fbd0ae85a056051012ba9 100644
--- a/base/posix/global_descriptors.h
+++ b/base/posix/global_descriptors.h
@@ -52,7 +52,18 @@
 
   // Often we want a canonical descriptor for a given Key. In this case, we add
   // the following constant to the key value:
+#if !defined(OS_ANDROID)
   static const int kBaseDescriptor = 3;  // 0, 1, 2 are already taken.
+#else
+  // 3 used by __android_log_write().
+  // 4 used by... something important on Android M.
+  // 5 used by... something important on Android L... on low-end devices.
+  // TODO(amistry): An Android, this mechanism is only used for tests since the
+  // content child launcher spawns a process by creating a new Activity using
+  // the Android APIs. For tests, come up with a way that doesn't require using
+  // a pre-defined fd.
+  static const int kBaseDescriptor = 6;
+#endif
 
   // Return the singleton instance of GlobalDescriptors.
   static GlobalDescriptors* GetInstance();