The correct type for the size of a chunk of memory is size_t.

content/browser/renderer_host/render_sandbox_host_linux.cc

Index: content/browser/renderer_host/render_sandbox_host_linux.cc
===================================================================
--- content/browser/renderer_host/render_sandbox_host_linux.cc	(revision 175576)
+++ content/browser/renderer_host/render_sandbox_host_linux.cc	(working copy)
@@ -391,8 +391,10 @@
                                      PickleIterator iter,
                                      std::vector<int>& fds) {
     base::SharedMemoryCreateOptions options;
-    if (!pickle.ReadUInt32(&iter, &options.size))
+    uint32_t size;
+    if (!pickle.ReadUInt32(&iter, &size))
       return;
+    options.size = size;
     if (!pickle.ReadBool(&iter, &options.executable))
       return;
     int shm_fd = -1;