Create libsampler as V8 sampler library.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 13943c9078e9b1440a536fe98a585ab0153f70aa..82023a4add3362f46abc61738c6608a66fc35ca9 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -105,6 +105,11 @@ config("libplatform_config") {
   include_dirs = [ "include" ]
 }
 
+# This config should be applied to code using the libsampler.
+config("libsampler_config") {
+  include_dirs = [ "include" ]
+}
+
 # This config should only be applied to code using V8 and not any V8 code
 # itself.
 config("external_config") {
@@ -1329,8 +1334,6 @@ v8_source_set("v8_base") {
     "src/profiler/profile-generator-inl.h",
     "src/profiler/profile-generator.cc",
     "src/profiler/profile-generator.h",
-    "src/profiler/sampler.cc",
-    "src/profiler/sampler.h",
     "src/profiler/sampling-heap-profiler.cc",
     "src/profiler/sampling-heap-profiler.h",
     "src/profiler/strings-storage.cc",
@@ -1816,6 +1819,7 @@ v8_source_set("v8_base") {
   defines = []
   deps = [
     ":v8_libbase",
+    ":v8_libsampler",
   ]
 
   if (is_win) {
@@ -1970,6 +1974,23 @@ v8_source_set("v8_libplatform") {
   ]
 }
 
+v8_source_set("v8_libsampler") {
+  sources = [
+    "src/libsampler/hashmap.h",
+    "src/libsampler/utils.h",
+    "src/libsampler/v8-sampler.cc",
+    "src/libsampler/v8-sampler.h",
+  ]
+
+  configs = [ ":internal_config_base" ]
+
+  public_configs = [ ":libsampler_config" ]
+
+  deps = [
+    ":v8_libbase",
+  ]
+}
+
 v8_source_set("fuzzer_support") {
   visibility = [ ":*" ]  # Only targets in this file can depend on this.