Remove Singleton from stats_config_util.cc

As part of our ongoing efforts to remove the dependency on Singleton,
this commit rewrites config/stats_config_util.cc without the Singleton
class dependency.

There should be no user observable change, including the fact that OSS
builds have been fixed to use NullStatsConfigUtilImpl at build time.

Author: yukawa

src/config/BUILD.bazel

@@ -98,9 +98,7 @@ mozc_cc_library(
     visibility = [
         "//:__subpackages__",
     ],
-    deps = [
-        "//base:singleton",
-    ] + mozc_select(
+    deps = mozc_select(
         android = [
             ":config_handler",
             "//protocol:config_cc_proto",
@@ -152,13 +150,6 @@ mozc_cc_test(
     ),
 )
 
-mozc_cc_library(
-    name = "stats_config_util_mock",
-    testonly = True,
-    hdrs = ["stats_config_util_mock.h"],
-    deps = [":stats_config_util"],
-)
-
 mozc_cc_library(
     name = "character_form_manager",
     srcs = ["character_form_manager.cc"],

src/config/stats_config_util.cc

@@ -29,8 +29,6 @@
 
 #include "config/stats_config_util.h"
 
-#include "base/singleton.h"
-
 #ifdef _WIN32
 #include <atlbase.h>
 #include <lmcons.h>
@@ -80,10 +78,10 @@ constexpr wchar_t kOmahaUsageKeyForEveryone[] =
 
 constexpr wchar_t kSendStatsName[] = L"usagestats";
 
-class WinStatsConfigUtilImpl : public StatsConfigUtilInterface {
+class WinStatsConfigUtilImpl {
  public:
-  bool IsEnabled() override;
-  bool SetEnabled(bool val) override;
+  static bool IsEnabled();
+  static bool SetEnabled(bool val);
 };
 
 bool WinStatsConfigUtilImpl::IsEnabled() {
@@ -156,10 +154,10 @@ std::string GetConfigFilePath() {
                       "/.usagestats.db");  // hidden file
 }
 
-class MacStatsConfigUtilImpl : public StatsConfigUtilInterface {
+class MacStatsConfigUtilImpl {
  public:
-  bool IsEnabled() override;
-  bool SetEnabled(bool val) override;
+  static bool IsEnabled();
+  static bool SetEnabled(bool val);
 };
 
 bool MacStatsConfigUtilImpl::IsEnabled() {
@@ -216,12 +214,12 @@ bool MacStatsConfigUtilImpl::SetEnabled(bool val) {
 #endif  // MACOSX
 
 #ifdef __ANDROID__
-class AndroidStatsConfigUtilImpl : public StatsConfigUtilInterface {
+class AndroidStatsConfigUtilImpl {
  public:
-  bool IsEnabled() override {
+  static bool IsEnabled() {
     return ConfigHandler::GetSharedConfig()->upload_usage_stats();
   }
-  bool SetEnabled(bool val) override {
+  static bool SetEnabled(bool val) {
     // TODO(horo): Implement this.
     return false;
   }
@@ -230,16 +228,12 @@ class AndroidStatsConfigUtilImpl : public StatsConfigUtilInterface {
 
 #endif  // GOOGLE_JAPANESE_INPUT_BUILD
 
-class NullStatsConfigUtilImpl : public StatsConfigUtilInterface {
+class NullStatsConfigUtilImpl {
  public:
-  bool IsEnabled() override { return false; }
-  bool SetEnabled(bool val) override { return true; }
+  static bool IsEnabled() { return false; }
+  static bool SetEnabled(bool val) { return true; }
 };
 
-StatsConfigUtilInterface* g_stats_config_util_handler = nullptr;
-
-// GetStatsConfigUtil and SetHandler are not thread safe.
-
 #if !defined(GOOGLE_JAPANESE_INPUT_BUILD)
 // For non-official build, use null implementation.
 typedef NullStatsConfigUtilImpl DefaultConfigUtilImpl;
@@ -254,23 +248,14 @@ typedef AndroidStatsConfigUtilImpl DefaultConfigUtilImpl;
 typedef NullStatsConfigUtilImpl DefaultConfigUtilImpl;
 #endif  // Platforms
 
-StatsConfigUtilInterface& GetStatsConfigUtil() {
-  if (g_stats_config_util_handler == nullptr) {
-    return *(Singleton<DefaultConfigUtilImpl>::get());
-  } else {
-    return *g_stats_config_util_handler;
-  }
-}
 }  // namespace
 
-void StatsConfigUtil::SetHandler(StatsConfigUtilInterface* handler) {
-  g_stats_config_util_handler = handler;
+bool StatsConfigUtil::IsEnabled() {
+  return DefaultConfigUtilImpl::IsEnabled();
 }
 
-bool StatsConfigUtil::IsEnabled() { return GetStatsConfigUtil().IsEnabled(); }
-
 bool StatsConfigUtil::SetEnabled(bool val) {
-  return GetStatsConfigUtil().SetEnabled(val);
+  return DefaultConfigUtilImpl::SetEnabled(val);
 }
 
 }  // namespace config

src/config/stats_config_util.h

@@ -33,18 +33,6 @@
 namespace mozc {
 namespace config {
 
-// Interface class
-class StatsConfigUtilInterface {
- public:
-  StatsConfigUtilInterface() = default;
-  StatsConfigUtilInterface(const StatsConfigUtilInterface&) = delete;
-  StatsConfigUtilInterface& operator=(const StatsConfigUtilInterface&) = delete;
-  virtual ~StatsConfigUtilInterface() = default;
-
-  virtual bool IsEnabled() = 0;
-  virtual bool SetEnabled(bool val) = 0;
-};
-
 class StatsConfigUtil {
  public:
   StatsConfigUtil() = delete;
@@ -62,11 +50,6 @@ class StatsConfigUtil {
   // Note: Administrative privilege is required in Windows.
   // Returns true if succeeded.
   static bool SetEnabled(bool val);
-
-  // Inject a dependency
-  static void SetHandler(StatsConfigUtilInterface* handler);
-
-  // Should never be allocated.
 };
 
 }  // namespace config