Update from https://crrev.com/315085

This includes the switch to libc++ on Android.

Other fixes:

*) Add (dumb) impl of OrderingBarrier() to command buffer
*) "base/debug/trace_event.h" -> "base/trace_event/trace_event.h"
*) Added a few <cmath> includes to sky

Review URL: https://codereview.chromium.org/903273002
diff --git a/gpu/command_buffer/service/command_buffer_service.cc b/gpu/command_buffer/service/command_buffer_service.cc
index 21e2ae4..f2444b3 100644
--- a/gpu/command_buffer/service/command_buffer_service.cc
+++ b/gpu/command_buffer/service/command_buffer_service.cc
@@ -79,6 +79,10 @@
     put_offset_change_callback_.Run();
 }
 
+void CommandBufferService::OrderingBarrier(int32 put_offset) {
+  Flush(put_offset);
+}
+
 void CommandBufferService::SetGetBuffer(int32 transfer_buffer_id) {
   DCHECK_EQ(-1, ring_buffer_id_);
   DCHECK_EQ(put_offset_, get_offset_);  // Only if it's empty.