Align base::hash_map with C++11.

cc/quads/render_pass.h

Index: cc/quads/render_pass.h
diff --git a/cc/quads/render_pass.h b/cc/quads/render_pass.h
index db42faf1e3ffa5cf2aeddc509116bc1f8a196314..2369cdfcf747b027f9de8771aad605384f3ac8da 100644
--- a/cc/quads/render_pass.h
+++ b/cc/quads/render_pass.h
@@ -130,20 +130,12 @@ class CC_EXPORT RenderPass {
 }  // namespace cc
 
 namespace BASE_HASH_NAMESPACE {
-#if defined(COMPILER_MSVC)
-inline size_t hash_value(const cc::RenderPassId& key) {
-  return base::HashPair(key.layer_id, key.index);
-}
-#elif defined(COMPILER_GCC)
 template <>
 struct hash<cc::RenderPassId> {
   size_t operator()(cc::RenderPassId key) const {
     return base::HashPair(key.layer_id, key.index);
   }
 };
-#else
-#error define a hash function for your compiler
-#endif  // COMPILER
 }  // namespace BASE_HASH_NAMESPACE
 
 namespace cc {