Align base::hash_map with C++11, part 1.

C++11's std::hash provides a default hash for T* that hashes by pointer value.
So does MSVC's stdext::hash_value, but not GCC's __gnu_cxx::hash (and STLPort's
std::hash). To align non-MSVC with both MSVC and the standard, provide a
default hash for pointers. This removes a lot of GCC-specific hash definitions.

Confusingly, all three provide a default hash for const char * that hashes as C
string, while not changing their equality. This CL does not change this on any
platform.

BUG=420242

Review URL: https://codereview.chromium.org/630503002

Cr-Commit-Position: refs/heads/master@{#299217}

base/containers/hash_tables.h

@@ -85,6 +85,17 @@ DEFINE_TRIVIAL_HASH(unsigned long long);
 #undef DEFINE_TRIVIAL_HASH
 #endif  // !defined(OS_ANDROID)
 
+// To align with C++11's std::hash and MSVC's pre-standard stdext::hash_value,
+// provide a default hash function for raw pointers. Note: const char * is still
+// specialized to hash as a C string. This is consistent with the currently used
+// stdext::hash_value, but not C++11.
+template<typename T>
+struct hash<T*> {
+  std::size_t operator()(T* value) const {
+    return hash<uintptr_t>()(reinterpret_cast<uintptr_t>(value));
+  }
+};
+
 // Implement string hash functions so that strings of various flavors can
 // be used as keys in STL maps and sets.  The hash algorithm comes from the
 // GNU C++ library, in <tr1/functional>.  It is duplicated here because GCC

base/debug/trace_event_impl.h

@@ -45,17 +45,6 @@
 template <typename Type>
 struct DefaultSingletonTraits;
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template <>
-struct hash<base::MessageLoop*> {
-  std::size_t operator()(base::MessageLoop* value) const {
-    return reinterpret_cast<std::size_t>(value);
-  }
-};
-}  // BASE_HASH_NAMESPACE
-#endif
-
 namespace base {
 
 class WaitableEvent;

base/memory/discardable_memory_manager.h

@@ -38,18 +38,6 @@ class DiscardableMemoryManagerAllocation {
 }  // namespace internal
 }  // namespace base
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template <>
-struct hash<base::internal::DiscardableMemoryManagerAllocation*> {
-  size_t operator()(
-      base::internal::DiscardableMemoryManagerAllocation* ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif  // COMPILER
-
 namespace base {
 namespace internal {
 

cc/resources/prioritized_resource_manager.h

@@ -19,16 +19,6 @@
 #include "cc/trees/proxy.h"
 #include "ui/gfx/size.h"
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template <> struct hash<cc::PrioritizedResource*> {
-  size_t operator()(cc::PrioritizedResource* ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif  // COMPILER
-
 namespace cc {
 
 class PriorityCalculator;

cc/trees/layer_sorter.h

@@ -16,19 +16,6 @@
 #include "ui/gfx/rect_f.h"
 #include "ui/gfx/vector3d_f.h"
 
-#if defined(COMPILER_GCC)
-namespace cc { struct GraphEdge; }
-
-namespace BASE_HASH_NAMESPACE {
-template <>
-struct hash<cc::GraphEdge*> {
-  size_t operator()(cc::GraphEdge* ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif  // COMPILER
-
 namespace gfx {
 class Transform;
 }

cc/trees/layer_tree_impl.h

@@ -18,17 +18,6 @@
 #include "cc/output/renderer.h"
 #include "cc/resources/ui_resource_client.h"
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template<>
-struct hash<cc::LayerImpl*> {
-  size_t operator()(cc::LayerImpl* ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif  // COMPILER
-
 namespace base {
 namespace debug {
 class TracedValue;

chrome/browser/download/chrome_download_manager_delegate.h

@@ -34,17 +34,6 @@ namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
-#if defined(COMPILER_GCC) && defined(ENABLE_EXTENSIONS)
-namespace BASE_HASH_NAMESPACE {
-template<>
-struct hash<extensions::CrxInstaller*> {
-  std::size_t operator()(extensions::CrxInstaller* const& p) const {
-    return reinterpret_cast<std::size_t>(p);
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif
-
 // This is the Chrome side helper for the download system.
 class ChromeDownloadManagerDelegate
     : public content::DownloadManagerDelegate,

chrome/browser/profiles/profile.h

@@ -407,17 +407,4 @@ struct ProfileCompare {
   bool operator()(Profile* a, Profile* b) const;
 };
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-
-template<>
-struct hash<Profile*> {
-  std::size_t operator()(Profile* const& p) const {
-    return reinterpret_cast<std::size_t>(p);
-  }
-};
-
-}  // namespace BASE_HASH_NAMESPACE
-#endif
-
 #endif  // CHROME_BROWSER_PROFILES_PROFILE_H_

chrome/browser/safe_browsing/protocol_manager.h

@@ -36,19 +36,6 @@ class URLFetcher;
 class URLRequestContextGetter;
 }  // namespace net
 
-#if defined(COMPILER_GCC)
-// Allows us to use URLFetchers in a hash_map with gcc (MSVC is okay without
-// specifying this).
-namespace BASE_HASH_NAMESPACE {
-template<>
-struct hash<const net::URLFetcher*> {
-  size_t operator()(const net::URLFetcher* fetcher) const {
-    return reinterpret_cast<size_t>(fetcher);
-  }
-};
-}
-#endif
-
 class SBProtocolManagerFactory;
 class SafeBrowsingProtocolManagerDelegate;
 

content/browser/manifest/manifest_manager_host.h

@@ -9,17 +9,6 @@
 #include "base/id_map.h"
 #include "content/public/browser/web_contents_observer.h"
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template<>
-struct hash<content::RenderFrameHost*> {
-  uint64 operator()(content::RenderFrameHost* ptr) const {
-    return hash<uint64>()(reinterpret_cast<uint64>(ptr));
-  }
-};
-}
-#endif
-
 namespace content {
 
 class RenderFrameHost;

content/child/npapi/np_channel_base.h

@@ -21,35 +21,6 @@ namespace base {
 class MessageLoopProxy;
 }
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-
-template<>
-struct hash<NPObject*> {
-  std::size_t operator()(NPObject* const& ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-
-template<>
-struct hash<struct _NPP*> {
-  std::size_t operator()(struct _NPP* const& ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-
-}  // namespace __gnu_cxx
-#elif defined(COMPILER_MSVC)
-namespace stdext {
-
-template<>
-inline size_t hash_value(NPObject* const& ptr) {
-  return hash_value(reinterpret_cast<size_t>(ptr));
-}
-
-}  // namespace stdext
-#endif // COMPILER
-
 namespace content {
 
 // Encapsulates an IPC channel between a renderer and another process. Used to

content/common/gpu/gpu_memory_manager_unittest.cc

@@ -12,17 +12,6 @@
 
 using gpu::MemoryAllocation;
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template<>
-struct hash<content::GpuMemoryManagerClient*> {
-  uint64 operator()(content::GpuMemoryManagerClient* ptr) const {
-    return hash<uint64>()(reinterpret_cast<uint64>(ptr));
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif  // COMPILER
-
 class FakeMemoryTracker : public gpu::gles2::MemoryTracker {
  public:
   virtual void TrackMemoryAllocatedChange(

content/public/browser/browser_context.h

@@ -168,17 +168,4 @@ class CONTENT_EXPORT BrowserContext : public base::SupportsUserData {
 
 }  // namespace content
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-
-template<>
-struct hash<content::BrowserContext*> {
-  std::size_t operator()(content::BrowserContext* const& p) const {
-    return reinterpret_cast<std::size_t>(p);
-  }
-};
-
-}  // namespace BASE_HASH_NAMESPACE
-#endif
-
 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_CONTEXT_H_

gpu/command_buffer/service/async_pixel_transfer_manager.h

@@ -15,17 +15,6 @@
 #include "gpu/command_buffer/service/texture_manager.h"
 #include "gpu/gpu_export.h"
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template <>
-  struct hash<gpu::gles2::TextureRef*> {
-  size_t operator()(gpu::gles2::TextureRef* ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif  // COMPILER
-
 namespace gfx {
 class GLContext;
 }

net/quic/quic_ack_notifier_manager.h

@@ -10,17 +10,6 @@
 #include "base/containers/hash_tables.h"
 #include "net/quic/quic_protocol.h"
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template<>
-struct hash<net::QuicAckNotifier*> {
-  std::size_t operator()(const net::QuicAckNotifier* ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-}
-#endif
-
 namespace net {
 
 class QuicAckNotifier;

tools/gn/target.h

@@ -315,20 +315,4 @@ class Target : public Item {
   DISALLOW_COPY_AND_ASSIGN(Target);
 };
 
-namespace BASE_HASH_NAMESPACE {
-
-#if defined(COMPILER_GCC)
-template<> struct hash<const Target*> {
-  std::size_t operator()(const Target* t) const {
-    return reinterpret_cast<std::size_t>(t);
-  }
-};
-#elif defined(COMPILER_MSVC)
-inline size_t hash_value(const Target* t) {
-  return reinterpret_cast<size_t>(t);
-}
-#endif  // COMPILER...
-
-}  // namespace BASE_HASH_NAMESPACE
-
 #endif  // TOOLS_GN_TARGET_H_