Align base::hash_map with C++11, part 2.

mojo/edk/system/channel_endpoint_id.h

Index: mojo/edk/system/channel_endpoint_id.h
diff --git a/mojo/edk/system/channel_endpoint_id.h b/mojo/edk/system/channel_endpoint_id.h
index 3643517575bdf97c62ee3a1e2a2417a231140b05..3636af7379caeb79555153808014c4c1a1d45c9f 100644
--- a/mojo/edk/system/channel_endpoint_id.h
+++ b/mojo/edk/system/channel_endpoint_id.h
@@ -13,7 +13,6 @@
 #include "base/containers/hash_tables.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
-#include "build/build_config.h"
 #include "mojo/edk/system/system_impl_export.h"
 
 namespace mojo {
@@ -133,11 +132,9 @@ class MOJO_SYSTEM_IMPL_EXPORT RemoteChannelEndpointIdGenerator {
 // Define "hash" functions for |ChannelEndpointId|s, so they can be used in hash
 // tables.
 // TODO(vtl): Once we can use |std::unordered_{map,set}|, update this (and
-// remove the base/containers/hash_tables.h and build/build_config.h includes).
+// remove the base/containers/hash_tables.h include).
 namespace BASE_HASH_NAMESPACE {
 
-#if defined(COMPILER_GCC)
-
 template <>
 struct hash<mojo::system::ChannelEndpointId> {
   size_t operator()(mojo::system::ChannelEndpointId channel_endpoint_id) const {
@@ -145,13 +142,6 @@ struct hash<mojo::system::ChannelEndpointId> {
   }
 };
 
-#elif defined(COMPILER_MSVC)
-
-inline size_t hash_value(mojo::system::ChannelEndpointId channel_endpoint_id) {
-  return static_cast<size_t>(channel_endpoint_id.value());
-}
-#endif
-
 }  // namespace BASE_HASH_NAMESPACE
 
 #endif  // MOJO_EDK_SYSTEM_CHANNEL_ENDPOINT_ID_H_