Turn libbase into a component

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 46c412626bb14e0f9239fc6f1cd7fa29ae9a926a..134f6a4450d9641aa5a744ba24f6fd255b5f1b88 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -130,6 +130,17 @@ config("libplatform_config") {
   include_dirs = [ "include" ]
 }
 
+# This config should be applied to code using the libbase.
+config("libbase_config") {
+  if (is_component_build) {
+    defines = [ "USING_V8_BASE_SHARED" ]
+  }
+  libs = []
+  if (is_android && current_toolchain != host_toolchain) {
+    libs += [ "log" ]
+  }
+}
+
 # This config should be applied to code using the libsampler.
 config("libsampler_config") {
   include_dirs = [ "include" ]
@@ -145,10 +156,6 @@ config("external_config") {
   if (v8_enable_inspector_override) {
     include_dirs += [ "$target_gen_dir/include" ]
   }
-  libs = []
-  if (is_android && current_toolchain != host_toolchain) {
-    libs += [ "log" ]
-  }
 }
 
 # This config should only be applied to code that needs to be explicitly
@@ -2149,9 +2156,7 @@ v8_source_set("v8_base") {
   }
 }
 
-v8_source_set("v8_libbase") {
-  visibility = [ ":*" ]  # Only targets in this file can depend on this.
-
+v8_component("v8_libbase") {
   sources = [
     "src/base/adapters.h",
     "src/base/atomic-utils.h",
@@ -2167,6 +2172,7 @@ v8_source_set("v8_libbase") {
     "src/base/atomicops_internals_x86_gcc.cc",
     "src/base/atomicops_internals_x86_gcc.h",
     "src/base/atomicops_internals_x86_msvc.h",
+    "src/base/base-export.h",
     "src/base/bits.cc",
     "src/base/bits.h",
     "src/base/build_config.h",
@@ -2217,8 +2223,14 @@ v8_source_set("v8_libbase") {
 
   configs = [ ":internal_config_base" ]
 
+  public_configs = [ ":libbase_config" ]
+
   defines = []
 
+  if (is_component_build) {
+    defines = [ "BUILDING_V8_BASE_SHARED" ]
+  }
+
   if (is_posix) {
     sources += [ "src/base/platform/platform-posix.cc" ]
   }
@@ -2362,6 +2374,7 @@ v8_source_set("fuzzer_support_nocomponent") {
   ]
 
   public_deps = [
+    ":v8_libbase",
     ":v8_libplatform",
   ]
 }
@@ -2390,6 +2403,7 @@ if (current_toolchain == v8_snapshot_toolchain) {
 
     deps = [
       ":v8_base",
+      ":v8_libbase",
       ":v8_libplatform",
       ":v8_nosnapshot",
       "//build/config/sanitizers:deps",
@@ -2512,6 +2526,7 @@ v8_executable("d8") {
   deps = [
     ":d8_js2c",
     ":v8",
+    ":v8_libbase",
     ":v8_libplatform",
     "//build/config/sanitizers:deps",
     "//build/win:default_exe_manifest",
@@ -2552,6 +2567,7 @@ v8_executable("v8_hello_world") {
 
   deps = [
     ":v8",
+    ":v8_libbase",
     ":v8_libplatform",
     "//build/config/sanitizers:deps",
     "//build/win:default_exe_manifest",
@@ -2576,6 +2592,7 @@ v8_executable("v8_sample_process") {
 
   deps = [
     ":v8",
+    ":v8_libbase",
     ":v8_libplatform",
     "//build/config/sanitizers:deps",
     "//build/win:default_exe_manifest",
@@ -2598,6 +2615,7 @@ v8_executable("v8_parser_shell") {
   ]
 
   deps = [
+    ":v8_libbase",
     ":v8_libplatform",
     "//build/config/sanitizers:deps",
     "//build/win:default_exe_manifest",
@@ -2641,6 +2659,7 @@ if (want_v8_shell) {
 
     deps = [
       ":v8",
+      ":v8_libbase",
       ":v8_libplatform",
       "//build/config/sanitizers:deps",
       "//build/win:default_exe_manifest",