base: Introduce SharedMemoryTracker for POSIX (but not macOS)

base/memory/shared_memory_posix.cc

Index: base/memory/shared_memory_posix.cc
diff --git a/base/memory/shared_memory_posix.cc b/base/memory/shared_memory_posix.cc
index 3a18faa83dd70e82c8381d33cc247afa270339a9..f0018c333fff52ccfcc63dac4764e7e64b1e976d 100644
--- a/base/memory/shared_memory_posix.cc
+++ b/base/memory/shared_memory_posix.cc
@@ -15,6 +15,7 @@
 #include "base/files/scoped_file.h"
 #include "base/logging.h"
 #include "base/memory/shared_memory_helper.h"
+#include "base/memory/shared_memory_tracker.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/posix/safe_strerror.h"
 #include "base/process/process_metrics.h"
@@ -283,8 +284,10 @@ bool SharedMemory::MapAt(off_t offset, size_t bytes) {
   bool mmap_succeeded = memory_ != (void*)-1 && memory_ != NULL;
   if (mmap_succeeded) {
     mapped_size_ = bytes;
-    DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
-        (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
+    DCHECK_EQ(0U,
+              reinterpret_cast<uintptr_t>(memory_) &
+                  (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
+    SharedMemoryTracker::GetInstance()->IncrementMemoryUsage(*this);
   } else {
     memory_ = NULL;
   }
@@ -297,6 +300,7 @@ bool SharedMemory::Unmap() {
     return false;
 
   munmap(memory_, mapped_size_);
+  SharedMemoryTracker::GetInstance()->DecrementMemoryUsage(*this);
   memory_ = NULL;
   mapped_size_ = 0;
   return true;
@@ -390,4 +394,14 @@ bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
   return true;
 }
 
+bool SharedMemory::GetUniqueId(SharedMemory::UniqueId* id) const {
+  base::ThreadRestrictions::AssertIOAllowed();
+  struct stat file_stat;
+  if (fstat(static_cast<int>(handle().fd), &file_stat) != 0)

[Primiano Tucci (use gerrit), 2017/02/27 14:10:50]

as this is a I/O syscall it might be safer to wrap in HANDLE_EINTR.
The linux manpage suggests it shouldn't be needed, but at the same time I have
no idea if the same applies to Android or Darwin

[hajimehoshi, 2017/02/28 06:59:25]

Done (Darwin doesn't reach here anyway).

+    return false;
+  id->first = file_stat.st_dev;
+  id->second = file_stat.st_ino;
+  return true;
+}
+
 }  // namespace base