NativeStackSampler implementation for Mac.

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index 11236dcd171b1a85d861094613942425e6432490..60e1929129a4f153626df2380ee652690af9e0c3 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -712,6 +712,7 @@ component("base") {
     "process/process_win.cc",
     "profiler/native_stack_sampler.cc",
     "profiler/native_stack_sampler.h",
+    "profiler/native_stack_sampler_mac.cc",
     "profiler/native_stack_sampler_posix.cc",
     "profiler/native_stack_sampler_win.cc",
     "profiler/scoped_profile.cc",
@@ -1451,6 +1452,10 @@ component("base") {
       "strings/sys_string_conversions_posix.cc",
       "threading/platform_thread_internal_posix.cc",
     ]
+
+    if (is_mac) {
+      sources -= [ "profiler/native_stack_sampler_posix.cc" ]
+    }
   } else {
     # Non-Mac/ios.
     sources -= [
@@ -1815,7 +1820,9 @@ if (is_win) {
       "//base/win:base_win_features",
     ]
   }
+}
 
+if (is_win || is_mac) {
   if (current_cpu == "x64") {
     # Must be a shared library so that it can be unloaded during testing.
     shared_library("base_profiler_test_support_library") {
@@ -2266,6 +2273,9 @@ test("base_unittests") {
       "CoreFoundation.framework",
       "Foundation.framework",
     ]
+    if (current_cpu == "x64") {
+      data_deps += [ ":base_profiler_test_support_library" ]
+    }
   }
 
   if (is_linux) {
@@ -2304,7 +2314,7 @@ test("base_unittests") {
     deps += [ "//base:scoped_handle_test_dll" ]
     if (current_cpu == "x64") {
       sources += [ "profiler/win32_stack_frame_unwinder_unittest.cc" ]
-      deps += [ ":base_profiler_test_support_library" ]
+      data_deps += [ ":base_profiler_test_support_library" ]

[Avi (use Gerrit), 2017/02/16 06:11:15]

How does this work without this change? A normal "deps" means that you're
hard-linking a requirement to this support library, which on the Mac at least
means that you can't unload it.

[Mike Wittman, 2017/02/16 21:51:34]

Apparently there's no corresponding restriction on Windows. I just verified that
the module gets unloaded in the test.

[Avi (use Gerrit), 2017/02/17 03:41:09]

:\

This is technically more correct, as the test intends to have an independent
library being loaded and unloaded, rather than unloading one that was
automatically loaded. I'm planning on leaving this in, even if it works today as
is.

[Mike Wittman, 2017/02/17 17:09:15]

I'm fine with this; my comment was just intended to provide context for what's
happening on Windows.

     }
   }