Revert of Remove raw handles from base::win::RegKey

base/win/registry.cc

Index: base/win/registry.cc
diff --git a/base/win/registry.cc b/base/win/registry.cc
index 8e7083fde7d3664d42fccbe072b9cd369d3f8b46..e8fb8922bc63cbefeaa34fce9ee942e3a07af685 100644
--- a/base/win/registry.cc
+++ b/base/win/registry.cc
@@ -34,74 +34,23 @@
 
 }  // namespace
 
-// Watches for modifications to a key.
-class RegKey::Watcher : public ObjectWatcher::Delegate {
- public:
-  explicit Watcher(RegKey* owner) : owner_(owner) {}
-  ~Watcher() {}
-
-  bool StartWatching(HKEY key, const ChangeCallback& callback);
-
-  // Implementation of ObjectWatcher::Delegate.
-  void OnObjectSignaled(HANDLE object) override {
-    DCHECK(watch_event_.IsValid() && watch_event_.Get() == object);
-    ChangeCallback callback = callback_;
-    callback_.Reset();
-    callback.Run();
-  }
-
- private:
-  RegKey* owner_;
-  ScopedHandle watch_event_;
-  ObjectWatcher object_watcher_;
-  ChangeCallback callback_;
-  DISALLOW_COPY_AND_ASSIGN(Watcher);
-};
-
-bool RegKey::Watcher::StartWatching(HKEY key, const ChangeCallback& callback) {
-  DCHECK(key);
-  DCHECK(callback_.is_null());
-  if (GetVersion() < VERSION_VISTA) {
-    // It is an error to register multiple times before Vista.
-    if (watch_event_.IsValid()) {
-      callback_ = callback;
-      return true;
-    }
-  }
-
-  if (!watch_event_.IsValid())
-    watch_event_.Set(CreateEvent(NULL, TRUE, FALSE, NULL));
-
-  if (!watch_event_.IsValid())
-    return false;
-
-  DWORD filter = REG_NOTIFY_CHANGE_NAME |
-                 REG_NOTIFY_CHANGE_ATTRIBUTES |
-                 REG_NOTIFY_CHANGE_LAST_SET |
-                 REG_NOTIFY_CHANGE_SECURITY;
-
-  // Watch the registry key for a change of value.
-  LONG result = RegNotifyChangeKeyValue(key, TRUE, filter, watch_event_.Get(),
-                                        TRUE);
-  if (result != ERROR_SUCCESS) {
-    watch_event_.Close();
-    return false;
-  }
-
-  callback_ = callback;
-  return object_watcher_.StartWatching(watch_event_.Get(), this);
-}
-
 // RegKey ----------------------------------------------------------------------
 
-RegKey::RegKey() : key_(NULL), wow64access_(0) {
-}
-
-RegKey::RegKey(HKEY key) : key_(key), wow64access_(0) {
+RegKey::RegKey()
+    : key_(NULL),
+      watch_event_(0),
+      wow64access_(0) {
+}
+
+RegKey::RegKey(HKEY key)
+    : key_(key),
+      watch_event_(0),
+      wow64access_(0) {
 }
 
 RegKey::RegKey(HKEY rootkey, const wchar_t* subkey, REGSAM access)
     : key_(NULL),
+      watch_event_(0),
       wow64access_(0) {
   if (rootkey) {
     if (access & (KEY_SET_VALUE | KEY_CREATE_SUB_KEY | KEY_CREATE_LINK))
@@ -201,6 +150,7 @@
 }
 
 void RegKey::Close() {
+  StopWatching();
   if (key_) {
     ::RegCloseKey(key_);
     key_ = NULL;
@@ -218,6 +168,7 @@
 
 HKEY RegKey::Take() {
   DCHECK(wow64access_ == 0);
+  StopWatching();
   HKEY key = key_;
   key_ = NULL;
   return key;
@@ -416,14 +367,44 @@
   return result;
 }
 
-bool RegKey::StartWatching(const ChangeCallback& callback) {
-  if (!key_watcher_)
-    key_watcher_.reset(new Watcher(this));
-
-  if (!key_watcher_.get()->StartWatching(key_, callback))
-    return false;
-
-  return true;
+LONG RegKey::StartWatching() {
+  DCHECK(key_);
+  if (!watch_event_)
+    watch_event_ = CreateEvent(NULL, TRUE, FALSE, NULL);
+
+  DWORD filter = REG_NOTIFY_CHANGE_NAME |
+                 REG_NOTIFY_CHANGE_ATTRIBUTES |
+                 REG_NOTIFY_CHANGE_LAST_SET |
+                 REG_NOTIFY_CHANGE_SECURITY;
+
+  // Watch the registry key for a change of value.
+  LONG result = RegNotifyChangeKeyValue(key_, TRUE, filter, watch_event_, TRUE);
+  if (result != ERROR_SUCCESS) {
+    CloseHandle(watch_event_);
+    watch_event_ = 0;
+  }
+
+  return result;
+}
+
+bool RegKey::HasChanged() {
+  if (watch_event_) {
+    if (WaitForSingleObject(watch_event_, 0) == WAIT_OBJECT_0) {
+      StartWatching();
+      return true;
+    }
+  }
+  return false;
+}
+
+LONG RegKey::StopWatching() {
+  LONG result = ERROR_INVALID_HANDLE;
+  if (watch_event_) {
+    CloseHandle(watch_event_);
+    watch_event_ = 0;
+    result = ERROR_SUCCESS;
+  }
+  return result;
 }
 
 // static