gpu: Add sync token dependencies to flush metadata.

gpu/command_buffer/common/sync_token.h

Index: gpu/command_buffer/common/sync_token.h
diff --git a/gpu/command_buffer/common/sync_token.h b/gpu/command_buffer/common/sync_token.h
index 6a6bfad2a9a8ba2ef8ebcfdea5ba3cf26151ab2c..990f0c9b4bd8c16ccfd8f804a78f7e7cf329e6b8 100644
--- a/gpu/command_buffer/common/sync_token.h
+++ b/gpu/command_buffer/common/sync_token.h
@@ -8,6 +8,8 @@
 #include <stdint.h>
 #include <string.h>
 
+#include <tuple>
+
 #include "gpu/command_buffer/common/command_buffer_id.h"
 #include "gpu/command_buffer/common/constants.h"
 #include "gpu/gpu_export.h"
@@ -77,13 +79,9 @@ struct GPU_EXPORT SyncToken {
   int32_t extra_data_field() const { return extra_data_field_; }
 
   bool operator<(const SyncToken& other) const {
-    // TODO(dyen): Once all our compilers support c++11, we can replace this
-    // long list of comparisons with std::tie().
-    return (namespace_id_ < other.namespace_id()) ||
-           ((namespace_id_ == other.namespace_id()) &&
-            ((command_buffer_id_ < other.command_buffer_id()) ||
-             ((command_buffer_id_ == other.command_buffer_id()) &&
-              (release_count_ < other.release_count()))));
+    return std::tie(namespace_id_, command_buffer_id_, release_count_) <
+           std::tie(other.namespace_id_, other.command_buffer_id_,
+                    other.release_count_);
   }
 
   bool operator==(const SyncToken& other) const {