libchrome: Fix libchrome build on Chrome OS

Applying libchrome r369476 changes to Chrome OS-only files from the
upstream of libchrome (from Chromium).

Also modified SConstruct to add new files and remove deleted files.

Change-Id: Id22160e32d19b0bb228903e3df372fb82550626c
diff --git a/SConstruct b/SConstruct
index e336a65..b316900 100644
--- a/SConstruct
+++ b/SConstruct
@@ -26,6 +26,7 @@
   {
     'name' : 'core',
     'sources' : """
+                allocator/allocator_extension.cc
                 at_exit.cc
                 base64.cc
                 base64url.cc
@@ -173,11 +174,11 @@
                 time/tick_clock.cc
                 time/time.cc
                 time/time_posix.cc
-                trace_event/heap_profiler_allocation_context.cc

-                trace_event/heap_profiler_allocation_context_tracker.cc

-                trace_event/heap_profiler_stack_frame_deduplicator.cc

-                trace_event/heap_profiler_type_name_deduplicator.cc

                 trace_event/malloc_dump_provider.cc
+                trace_event/heap_profiler_allocation_context.cc
+                trace_event/heap_profiler_allocation_context_tracker.cc
+                trace_event/heap_profiler_stack_frame_deduplicator.cc
+                trace_event/heap_profiler_type_name_deduplicator.cc
                 trace_event/memory_allocator_dump.cc
                 trace_event/memory_allocator_dump_guid.cc
                 trace_event/memory_dump_manager.cc
@@ -194,16 +195,16 @@
                 trace_event/trace_event_impl.cc
                 trace_event/trace_event_memory_overhead.cc
                 trace_event/trace_event_synthetic_delay.cc
-                trace_event/trace_log.cc

-                trace_event/trace_log_constants.cc

-                trace_event/trace_sampling_thread.cc

+                trace_event/trace_log.cc
+                trace_event/trace_log_constants.cc
+                trace_event/trace_sampling_thread.cc
                 tracked_objects.cc
                 tracking_info.cc
                 values.cc
                 vlog.cc
                 """,
     'prefix' : 'base',
-    'libs' : 'pthread rt',
+    'libs' : 'pthread rt libmodp_b64',
     'pc_libs' : 'glib-2.0 libevent',
   },
   {
@@ -282,7 +283,6 @@
                 linux/bpf_dsl/syscall_set.cc
                 linux/bpf_dsl/verifier.cc
                 linux/seccomp-bpf/die.cc
-                linux/seccomp-bpf/errorcode.cc
                 linux/seccomp-bpf/sandbox_bpf.cc
                 linux/seccomp-bpf/syscall.cc
                 linux/seccomp-bpf/trap.cc