Mojo: COMPILE_ASSERT -> static_assert in mojo/system and mojo/embedder.

mojo/system/channel.cc

Index: mojo/system/channel.cc
diff --git a/mojo/system/channel.cc b/mojo/system/channel.cc
index 3114a59106c9e2b5f5bb3d02ab2ae06cb5dd1ca9..994863f6013018760d817abbb93e28890c70e507 100644
--- a/mojo/system/channel.cc
+++ b/mojo/system/channel.cc
@@ -18,9 +18,9 @@
 namespace mojo {
 namespace system {
 
-COMPILE_ASSERT(Channel::kBootstrapEndpointId !=
-                   MessageInTransit::kInvalidEndpointId,
-               kBootstrapEndpointId_is_invalid);
+static_assert(Channel::kBootstrapEndpointId !=
+                  MessageInTransit::kInvalidEndpointId,
+              "kBootstrapEndpointId is invalid");
 
 STATIC_CONST_MEMBER_DEFINITION const MessageInTransit::EndpointId
     Channel::kBootstrapEndpointId;