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

MSVC's stdext::hash_map, unlike C++11's std::unordered_map and GCC's
__gnu_cxx::hash_map, requires a total order on the key. It also has a very
different syntax for supplying a default hash function.

Switch MSVC to std::unordered_map, but exposed as base::hash_map. This aligns
both the container and the default hash function. The default hash function now
differs from our GCC one in that const char * is no longer hashed as a C string.

To align GCC with C++11 semantics and the MSVC ones this CL introduces, also
provide a new hash function and swap the default hash with it. This new
function is identical to __gnu_cxx::hash, but it does not specialize const
char* and does specialize T* (which was already aligned by
https://codereview.chromium.org/630503002/).

Note: This CL changes a file in mojo/ and will need to be mirrored in the
mojo repository before the next sync.

BUG=420242

Review URL: https://codereview.chromium.org/623383002

Cr-Commit-Position: refs/heads/master@{#301185}

1 files changed, 0 insertions, 8 deletions

diff --git a/cc/quads/render_pass.h b/cc/quads/render_pass.h
index 76536b5..2877588 100644
--- a/cc/quads/render_pass.h
+++ b/cc/quads/render_pass.h
@@ -133,20 +133,12 @@ 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 {