base: Introduce SharedMemoryTracker for POSIX (but not macOS)

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index fa5e369d68a7df4b924f93cd774f22b95f5672d5..75dcf69ccbea4f1cdab8bbd2856d598188a491bf 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -519,12 +519,15 @@ component("base") {
     "memory/shared_memory_android.cc",
     "memory/shared_memory_handle.h",
     "memory/shared_memory_handle_mac.cc",
+    "memory/shared_memory_handle_posix.cc",
     "memory/shared_memory_handle_win.cc",
     "memory/shared_memory_helper.cc",
     "memory/shared_memory_helper.h",
     "memory/shared_memory_mac.cc",
     "memory/shared_memory_nacl.cc",
     "memory/shared_memory_posix.cc",
+    "memory/shared_memory_tracker.cc",
+    "memory/shared_memory_tracker.h",
     "memory/shared_memory_win.cc",
     "memory/singleton.cc",
     "memory/singleton.h",
@@ -1400,6 +1403,7 @@ component("base") {
   # Mac or iOS.
   if (is_mac || is_ios) {
     sources -= [
+      "memory/shared_memory_handle_posix.cc",
       "memory/shared_memory_posix.cc",
       "native_library_posix.cc",
       "strings/sys_string_conversions_posix.cc",
@@ -1517,6 +1521,7 @@ component("base") {
       "mac/scoped_objc_class_swizzler.h",
       "mac/scoped_objc_class_swizzler.mm",
       "mac/scoped_typeref.h",
+      "memory/shared_memory_handle_posix.cc",
       "memory/shared_memory_posix.cc",
       "message_loop/message_pump_mac.h",
       "message_loop/message_pump_mac.mm",
@@ -1534,6 +1539,13 @@ component("base") {
     sources += [ "power_monitor/power_monitor_device_source_posix.cc" ]
   }
 
+  if (!(is_posix && !is_mac)) {

[danakj, 2017/01/25 16:58:12]

can you write this without double negatives?

also while most of this uses sources -= [] we'd like to move toward using
sources += [] instead only. Can you do that with these new files?

[hajimehoshi, 2017/01/26 10:56:00]

Done.

+    sources -= [
+      "memory/shared_memory_tracker.cc",
+      "memory/shared_memory_tracker.h",
+    ]
+  }
+
   if (!use_glib) {
     sources -= [
       "message_loop/message_pump_glib.cc",