Update from https://crrev.com/333737

base/memory/shared_memory.h

Index: base/memory/shared_memory.h
diff --git a/base/memory/shared_memory.h b/base/memory/shared_memory.h
index d76e01c6e57612024fe35dc7c430229d89cd5112..008bb0106688c56f66e7edea893de42b5c5c0f5a 100644
--- a/base/memory/shared_memory.h
+++ b/base/memory/shared_memory.h
@@ -34,10 +34,7 @@ class FilePath;
 #if defined(OS_WIN)
 typedef HANDLE SharedMemoryHandle;
 #elif defined(OS_POSIX)
-// A SharedMemoryId is sufficient to identify a given shared memory segment on a
-// system, but insufficient to map it.
 typedef FileDescriptor SharedMemoryHandle;
-typedef ino_t SharedMemoryId;
 #endif
 
 // Options for creating a shared memory object.
@@ -116,6 +113,21 @@ class BASE_EXPORT SharedMemory {
   // Returns the maximum number of handles that can be open at once per process.
   static size_t GetHandleLimit();
 
+  // Duplicates The underlying OS primitive. Returns NULLHandle() on failure.
+  // The caller is responsible for destroying the duplicated OS primitive.
+  static SharedMemoryHandle DuplicateHandle(const SharedMemoryHandle& handle);
+
+#if defined(OS_POSIX)
+  // This method requires that the SharedMemoryHandle is backed by a POSIX fd.
+  static int GetFdFromSharedMemoryHandle(const SharedMemoryHandle& handle);
+#endif
+
+#if defined(OS_POSIX) && !defined(OS_ANDROID)
+  // Returns the size of the shared memory region referred to by |handle|.
+  // Returns '-1' on a failure to determine the size.
+  static int GetSizeFromSharedMemoryHandle(const SharedMemoryHandle& handle);
+#endif  // defined(OS_POSIX) && !defined(OS_ANDROID)
+
   // Creates a shared memory object as described by the options struct.
   // Returns true on success and false on failure.
   bool Create(const SharedMemoryCreateOptions& options);
@@ -192,14 +204,6 @@ class BASE_EXPORT SharedMemory {
   // identifier is not portable.
   SharedMemoryHandle handle() const;
 
-#if defined(OS_POSIX) && !defined(OS_NACL)
-  // Returns a unique identifier for this shared memory segment. Inode numbers
-  // are technically only unique to a single filesystem. However, we always
-  // allocate shared memory backing files from the same directory, so will end
-  // up on the same filesystem.
-  SharedMemoryId id() const { return inode_; }
-#endif
-
   // Closes the open shared memory segment. The memory will remain mapped if
   // it was previously mapped.
   // It is safe to call Close repeatedly.
@@ -289,7 +293,6 @@ class BASE_EXPORT SharedMemory {
 #elif defined(OS_POSIX)
   int                mapped_file_;
   int                readonly_mapped_file_;
-  ino_t              inode_;
 #endif
   size_t             mapped_size_;
   void*              memory_;