Update from https://crrev.com/320343

base/memory/shared_memory_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/memory/shared_memory.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/process/process_metrics.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/safe_strerror_posix.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_restrictions.h"
 
 #if defined(OS_MACOSX)
 #include "base/mac/foundation_util.h"
 #endif  // OS_MACOSX
 
@@ skipping 82 matching lines @@
 }
 
 #if !defined(OS_ANDROID)
 // Chromium mostly only uses the unique/private shmem as specified by
 // "name == L"". The exception is in the StatsTable.
 // TODO(jrg): there is no way to "clean up" all unused named shmem if
 // we restart from a crash.  (That isn't a new problem, but it is a problem.)
 // In case we want to delete it later, it may be useful to save the value
 // of mem_filename after FilePathForMemoryName().
 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
+  // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/466437
+  // is fixed.
+  tracked_objects::ScopedTracker tracking_profile1(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "466437 SharedMemory::Create::Start"));
   DCHECK_EQ(-1, mapped_file_);
   if (options.size == 0) return false;
 
   if (options.size > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
   // This function theoretically can block on the disk, but realistically
   // the temporary files we create will just go into the buffer cache
   // and be deleted before they ever make it out to disk.
   base::ThreadRestrictions::ScopedAllowIO allow_io;
 
   ScopedFILE fp;
   bool fix_size = true;
   ScopedFD readonly_fd;
 
   FilePath path;
   if (options.name_deprecated == NULL || options.name_deprecated->empty()) {
     // It doesn't make sense to have a open-existing private piece of shmem
     DCHECK(!options.open_existing_deprecated);
     // Q: Why not use the shm_open() etc. APIs?
     // A: Because they're limited to 4mb on OS X.  FFFFFFFUUUUUUUUUUU
     FilePath directory;
-    if (GetShmemTempDir(options.executable, &directory))
+    if (GetShmemTempDir(options.executable, &directory)) {
+      // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/466437
+      // is fixed.
+      tracked_objects::ScopedTracker tracking_profile2(
+          FROM_HERE_WITH_EXPLICIT_FUNCTION(
+              "466437 SharedMemory::Create::OpenTemporaryFile"));
       fp.reset(CreateAndOpenTemporaryFileInDir(directory, &path));
+    }
 
     if (fp) {
       if (options.share_read_only) {
+        // TODO(erikchen): Remove ScopedTracker below once
+        // http://crbug.com/466437 is fixed.
+        tracked_objects::ScopedTracker tracking_profile3(
+            FROM_HERE_WITH_EXPLICIT_FUNCTION(
+                "466437 SharedMemory::Create::OpenReadonly"));
         // Also open as readonly so that we can ShareReadOnlyToProcess.
         readonly_fd.reset(HANDLE_EINTR(open(path.value().c_str(), O_RDONLY)));
         if (!readonly_fd.is_valid()) {
           DPLOG(ERROR) << "open(\"" << path.value() << "\", O_RDONLY) failed";
           fp.reset();
           return false;
         }
       }
+
+      // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/466437
+      // is fixed.
+      tracked_objects::ScopedTracker tracking_profile4(
+          FROM_HERE_WITH_EXPLICIT_FUNCTION(
+              "466437 SharedMemory::Create::Unlink"));
       // Deleting the file prevents anyone else from mapping it in (making it
       // private), and prevents the need for cleanup (once the last fd is
       // closed, it is truly freed).
       if (unlink(path.value().c_str()))
         PLOG(WARNING) << "unlink";
     }
   } else {
     if (!FilePathForMemoryName(*options.name_deprecated, &path))
       return false;
 
@@ skipping 280 matching lines @@
                                         bool close_self,
                                         ShareMode share_mode) {
   int handle_to_dup = -1;
   switch(share_mode) {
     case SHARE_CURRENT_MODE:
       handle_to_dup = mapped_file_;
       break;
     case SHARE_READONLY:
       // We could imagine re-opening the file from /dev/fd, but that can't make
       // it readonly on Mac: https://codereview.chromium.org/27265002/#msg10
-      CHECK(readonly_mapped_file_ >= 0);
+      CHECK_GE(readonly_mapped_file_, 0);
       handle_to_dup = readonly_mapped_file_;
       break;
   }
 
   const int new_fd = dup(handle_to_dup);
   if (new_fd < 0) {
     DPLOG(ERROR) << "dup() failed.";
     return false;
   }
 
   new_handle->fd = new_fd;
   new_handle->auto_close = true;
 
   if (close_self) {
     Unmap();
     Close();
   }
 
   return true;
 }
 
 }  // namespace base