Mojo: Make room for remotely-allocated channel endpoint IDs.

mojo/edk/system/channel_endpoint_id.cc

Index: mojo/edk/system/channel_endpoint_id.cc
diff --git a/mojo/edk/system/channel_endpoint_id.cc b/mojo/edk/system/channel_endpoint_id.cc
index edbf3352f0771468160d4cc41eb8159bcdd65957..3c51cfe144ee6b17d2588a903646ea9161b50f3f 100644
--- a/mojo/edk/system/channel_endpoint_id.cc
+++ b/mojo/edk/system/channel_endpoint_id.cc
@@ -4,12 +4,20 @@
 
 #include "mojo/edk/system/channel_endpoint_id.h"
 
+#include "base/compiler_specific.h"
+
 namespace mojo {
 namespace system {
 
+STATIC_CONST_MEMBER_DEFINITION const uint32_t
+    ChannelEndpointId::kRemotelyAllocatedFlag;
+STATIC_CONST_MEMBER_DEFINITION const uint32_t
+    ChannelEndpointId::kLocallyAllocatedMask;
+
 ChannelEndpointId LocalChannelEndpointIdGenerator::GetNext() {
   ChannelEndpointId rv = next_channel_endpoint_id_;
-  next_channel_endpoint_id_.value_++;
+  next_channel_endpoint_id_.value_ = (next_channel_endpoint_id_.value_ + 1) &
+                                     ChannelEndpointId::kLocallyAllocatedMask;
   // Skip over the invalid value, in case we wrap.
   if (!next_channel_endpoint_id_.is_valid())
     next_channel_endpoint_id_.value_++;