Use std::tie() for operator< in cc/

Simplify the code for operator< when comparing multiple members using
a common std::tie idiom.

BUG=555171
R=danakj@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1463623002

Cr-Commit-Position: refs/heads/master@{#360872}

2 files changed, 7 insertions, 5 deletions

diff --git a/cc/quads/render_pass_id.h b/cc/quads/render_pass_id.h
index 9c36f32..f6ab9ce 100644
--- a/cc/quads/render_pass_id.h
+++ b/cc/quads/render_pass_id.h
@@ -5,6 +5,8 @@
 #ifndef CC_QUADS_RENDER_PASS_ID_H_
 #define CC_QUADS_RENDER_PASS_ID_H_
 
+#include <tuple>
+
 #include "base/basictypes.h"
 #include "base/containers/hash_tables.h"
 #include "cc/base/cc_export.h"
@@ -27,8 +29,7 @@ class CC_EXPORT RenderPassId {
   }
   bool operator!=(const RenderPassId& other) const { return !(*this == other); }
   bool operator<(const RenderPassId& other) const {
-    return layer_id < other.layer_id ||
-           (layer_id == other.layer_id && index < other.index);
+    return std::tie(layer_id, index) < std::tie(other.layer_id, other.index);
   }
 };
 
diff --git a/cc/surfaces/surface_sequence.h b/cc/surfaces/surface_sequence.h
index 72f4bc9..b579296 100644
--- a/cc/surfaces/surface_sequence.h
+++ b/cc/surfaces/surface_sequence.h
@@ -5,6 +5,8 @@
 #ifndef CC_SURFACES_SURFACE_SEQUENCE_H_
 #define CC_SURFACES_SURFACE_SEQUENCE_H_
 
+#include <tuple>
+
 #include "base/containers/hash_tables.h"
 
 namespace cc {
@@ -31,9 +33,8 @@ inline bool operator!=(const SurfaceSequence& a, const SurfaceSequence& b) {
 }
 
 inline bool operator<(const SurfaceSequence& a, const SurfaceSequence& b) {
-  if (a.id_namespace != b.id_namespace)
-    return a.id_namespace < b.id_namespace;
-  return a.sequence < b.sequence;
+  return std::tie(a.id_namespace, a.sequence) <
+         std::tie(b.id_namespace, b.sequence);
 }
 
 }  // namespace cc