Add a GUID to base::SharedMemoryHandle.

base/memory/shared_memory_handle.h

Index: base/memory/shared_memory_handle.h
diff --git a/base/memory/shared_memory_handle.h b/base/memory/shared_memory_handle.h
index 044c9c983a6c0fdc60461d9820befc61b315d172..56165b403b9b18b7eafead80e853c32c51e95bab 100644
--- a/base/memory/shared_memory_handle.h
+++ b/base/memory/shared_memory_handle.h
@@ -7,6 +7,7 @@
 
 #include <stddef.h>
 
+#include "base/unguessable_token.h"
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
@@ -61,6 +62,8 @@ class BASE_EXPORT SharedMemoryHandle {
   // resource.
   SharedMemoryHandle Duplicate() const;
 
+  base::UnguessableToken GetGUID() const;

[Nico, 2017/05/04 17:42:13]

add comment saying what this is good for

[erikchen, 2017/05/04 19:21:13]

Done.

+
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   enum Type {
     // The SharedMemoryHandle is backed by a POSIX fd.
@@ -76,15 +79,18 @@ class BASE_EXPORT SharedMemoryHandle {
   // common for existing code to make shallow copies of SharedMemoryHandle, and
   // the one that is finally passed into a base::SharedMemory is the one that
   // "consumes" the fd.

[Nico, 2017/05/04 17:42:13]

mention what the guid is for (can people who don't want to share their fd pass
some default empty guid?)

[erikchen, 2017/05/04 19:21:12]

Done.

-  explicit SharedMemoryHandle(const base::FileDescriptor& file_descriptor);
+  SharedMemoryHandle(const base::FileDescriptor& file_descriptor,
+                     const base::UnguessableToken& guid);
 
   // Makes a Mach-based SharedMemoryHandle of the given size. On error,
   // subsequent calls to IsValid() return false.
-  explicit SharedMemoryHandle(mach_vm_size_t size);
+  SharedMemoryHandle(mach_vm_size_t size, const base::UnguessableToken& guid);
 
   // Makes a Mach-based SharedMemoryHandle from |memory_object|, a named entry
   // in the current task. The memory region has size |size|.
-  SharedMemoryHandle(mach_port_t memory_object, mach_vm_size_t size);
+  SharedMemoryHandle(mach_port_t memory_object,
+                     mach_vm_size_t size,
+                     const base::UnguessableToken& guid);
 
   // Exposed so that the SharedMemoryHandle can be transported between
   // processes.
@@ -100,16 +106,12 @@ class BASE_EXPORT SharedMemoryHandle {
   // mapped memory.
   bool MapAt(off_t offset, size_t bytes, void** memory, bool read_only);
 #elif defined(OS_WIN)
-  // Takes implicit ownership of |h|.
-  SharedMemoryHandle(HANDLE h);
-
+  // Takes implicit ownership of |h|, with the given |guid|.
+  SharedMemoryHandle(HANDLE h, const base::UnguessableToken& guid);
   HANDLE GetHandle() const;
 #else
-  // This constructor is deprecated, as it fails to propagate the GUID, which
-  // will be added in the near future.
-  // TODO(rockot): Remove this constructor once Mojo supports GUIDs.
-  // https://crbug.com/713763.
-  explicit SharedMemoryHandle(const base::FileDescriptor& file_descriptor);
+  SharedMemoryHandle(const base::FileDescriptor& file_descriptor,
+                     const base::UnguessableToken& guid);
 
   // Creates a SharedMemoryHandle from an |fd| supplied from an external
   // service.
@@ -130,9 +132,6 @@ class BASE_EXPORT SharedMemoryHandle {
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   friend class SharedMemory;
 
-  // Shared code between copy constructor and operator=.
-  void CopyRelevantData(const SharedMemoryHandle& handle);
-
   Type type_;
 
   // Each instance of a SharedMemoryHandle is backed either by a POSIX fd or a
@@ -166,6 +165,9 @@ class BASE_EXPORT SharedMemoryHandle {
 #else
   FileDescriptor file_descriptor_;
 #endif
+
+  // Uniques identifies the SharedMemoryHandle. Preserved across IPC.
+  base::UnguessableToken guid_;
 };
 
 }  // namespace base