Cleanup: add const AddObserver method to TaskRunnerBoundObserverList

To deprecate TaskRunnerBoundObserverList::Source, which tends to
add more code just to ensure constness of the observer list.

BUG=241701
TEST=no behavioral changes (content_unittests:*File*)
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/18943006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@211356 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 34 insertions, 59 deletions

diff --git a/webkit/browser/fileapi/mock_file_change_observer.cc b/webkit/browser/fileapi/mock_file_change_observer.cc
index e72a389..74791f5 100644
--- a/webkit/browser/fileapi/mock_file_change_observer.cc
+++ b/webkit/browser/fileapi/mock_file_change_observer.cc
@@ -19,9 +19,8 @@ MockFileChangeObserver::~MockFileChangeObserver() {}
 // static
 ChangeObserverList MockFileChangeObserver::CreateList(
     MockFileChangeObserver* observer) {
-  ChangeObserverList::Source source;
-  source.AddObserver(observer, base::MessageLoopProxy::current().get());
-  return ChangeObserverList(source);
+  ChangeObserverList list;
+  return list.AddObserver(observer, base::MessageLoopProxy::current().get());
 }
 
 void MockFileChangeObserver::OnCreateFile(const FileSystemURL& url) {
diff --git a/webkit/browser/fileapi/sandbox_file_system_backend.cc b/webkit/browser/fileapi/sandbox_file_system_backend.cc
index b1256ff..f81af13 100644
--- a/webkit/browser/fileapi/sandbox_file_system_backend.cc
+++ b/webkit/browser/fileapi/sandbox_file_system_backend.cc
@@ -143,18 +143,15 @@ SandboxFileSystemBackend::SandboxFileSystemBackend(
               kDisableUsageTracking)),
       weak_factory_(this) {
   // Set quota observers.
-  UpdateObserverList::Source update_observers_src;
-  AccessObserverList::Source access_observers_src;
-
   if (enable_usage_tracking_) {
-    update_observers_src.AddObserver(sandbox_context_->quota_observer(),
-                                     sandbox_context_->file_task_runner());
-    access_observers_src.AddObserver(sandbox_context_->quota_observer(), NULL);
+    update_observers_ = update_observers_.AddObserver(
+        sandbox_context_->quota_observer(),
+        sandbox_context_->file_task_runner());
+    access_observers_ = access_observers_.AddObserver(
+        sandbox_context_->quota_observer(), NULL);
   }
 
-  update_observers_ = UpdateObserverList(update_observers_src);
-  access_observers_ = AccessObserverList(access_observers_src);
-  syncable_update_observers_ = UpdateObserverList(update_observers_src);
+  syncable_update_observers_ = update_observers_;
 
   if (!sandbox_context_->file_task_runner()->RunsTasksOnCurrentThread()) {
     // Post prepopulate task only if it's not already running on
@@ -462,9 +459,7 @@ void SandboxFileSystemBackend::AddFileUpdateObserver(
   UpdateObserverList* list = &update_observers_;
   if (type == kFileSystemTypeSyncable)
     list = &syncable_update_observers_;
-  UpdateObserverList::Source observer_source = list->source();
-  observer_source.AddObserver(observer, task_runner);
-  *list = UpdateObserverList(observer_source);
+  *list = list->AddObserver(observer, task_runner);
 }
 
 void SandboxFileSystemBackend::AddFileChangeObserver(
@@ -475,9 +470,7 @@ void SandboxFileSystemBackend::AddFileChangeObserver(
   ChangeObserverList* list = &change_observers_;
   if (type == kFileSystemTypeSyncable)
     list = &syncable_change_observers_;
-  ChangeObserverList::Source observer_source = list->source();
-  observer_source.AddObserver(observer, task_runner);
-  *list = ChangeObserverList(observer_source);
+  *list = list->AddObserver(observer, task_runner);
 }
 
 void SandboxFileSystemBackend::AddFileAccessObserver(
@@ -485,10 +478,7 @@ void SandboxFileSystemBackend::AddFileAccessObserver(
     FileAccessObserver* observer,
     base::SequencedTaskRunner* task_runner) {
   DCHECK(CanHandleType(type));
-  AccessObserverList* list = &access_observers_;
-  AccessObserverList::Source observer_source = list->source();
-  observer_source.AddObserver(observer, task_runner);
-  *list = AccessObserverList(observer_source);
+  access_observers_ = access_observers_.AddObserver(observer, task_runner);
 }
 
 const UpdateObserverList* SandboxFileSystemBackend::GetUpdateObservers(
diff --git a/webkit/browser/fileapi/task_runner_bound_observer_list.h b/webkit/browser/fileapi/task_runner_bound_observer_list.h
index 974447d..36a3393 100644
--- a/webkit/browser/fileapi/task_runner_bound_observer_list.h
+++ b/webkit/browser/fileapi/task_runner_bound_observer_list.h
@@ -34,37 +34,32 @@ void NotifyWrapper(T obj, Method m, const Params& p) {
 template <class Observer, class ObserverStoreType = Observer*>
 class TaskRunnerBoundObserverList {
  public:
-  // A constructor parameter class.
-  class Source {
-   public:
-    typedef scoped_refptr<base::SequencedTaskRunner> TaskRunnerPtr;
-    typedef std::map<ObserverStoreType, TaskRunnerPtr> ObserversListMap;
-
-    // Add |observer| to the list parameter. The |observer| will be notified on
-    // the |runner_to_notify| runner.  It is valid to give NULL as
-    // |runner_to_notify| (in such case notifications are dispatched on
-    // the current runner).
-    void AddObserver(Observer* observer,
-                     base::SequencedTaskRunner* runner_to_notify) {
-      observers_.insert(std::make_pair(observer, runner_to_notify));
-    }
-
-    const ObserversListMap& observers() const { return observers_; }
-
-   private:
-    ObserversListMap observers_;
-  };
+  typedef scoped_refptr<base::SequencedTaskRunner> TaskRunnerPtr;
+  typedef std::map<ObserverStoreType, TaskRunnerPtr> ObserversListMap;
 
   // Creates an empty list.
   TaskRunnerBoundObserverList<Observer, ObserverStoreType>() {}
 
-  // Creates a new list with given |observers_param|.
+  // Creates a new list with given |observers|.
   explicit TaskRunnerBoundObserverList<Observer, ObserverStoreType>(
-      const Source& observers)
-      : source_(observers) {}
+      const ObserversListMap& observers)
+      : observers_(observers) {}
 
   virtual ~TaskRunnerBoundObserverList<Observer, ObserverStoreType>() {}
 
+  // Returns a new observer list with given observer.
+  // It is valid to give NULL as |runner_to_notify|, and in that case
+  // notifications are dispatched on the current runner.
+  // Note that this is a const method and does NOT change 'this' observer
+  // list but returns a new list.
+  TaskRunnerBoundObserverList<Observer, ObserverStoreType> AddObserver(
+      Observer* observer,
+      base::SequencedTaskRunner* runner_to_notify) const {
+    ObserversListMap observers = observers_;
+    observers.insert(std::make_pair(observer, runner_to_notify));
+    return TaskRunnerBoundObserverList<Observer, ObserverStoreType>(observers);
+  }
+
   // Notify on the task runner that is given to AddObserver.
   // If we're already on the runner this just dispatches the method.
   template <class Method, class Params>
@@ -72,9 +67,8 @@ class TaskRunnerBoundObserverList {
     COMPILE_ASSERT(
         (base::internal::ParamsUseScopedRefptrCorrectly<Params>::value),
         badunboundmethodparams);
-    for (typename ObserversListMap::const_iterator it =
-            source_.observers().begin();
-         it != source_.observers().end(); ++it) {
+    for (typename ObserversListMap::const_iterator it = observers_.begin();
+         it != observers_.end(); ++it) {
       if (!it->second.get() || it->second->RunsTasksOnCurrentThread()) {
         DispatchToMethod(UnwrapTraits::Unwrap(it->first), method, params);
         continue;
@@ -86,14 +80,10 @@ class TaskRunnerBoundObserverList {
     }
   }
 
-  const Source& source() const { return source_; }
-
  private:
   typedef base::internal::UnwrapTraits<ObserverStoreType> UnwrapTraits;
-  typedef scoped_refptr<base::SequencedTaskRunner> TaskRunnerPtr;
-  typedef std::map<ObserverStoreType, TaskRunnerPtr> ObserversListMap;
 
-  Source source_;
+  ObserversListMap observers_;
 };
 
 class FileAccessObserver;
diff --git a/webkit/browser/fileapi/test_file_system_backend.cc b/webkit/browser/fileapi/test_file_system_backend.cc
index dbbeb4f..700cc0d 100644
--- a/webkit/browser/fileapi/test_file_system_backend.cc
+++ b/webkit/browser/fileapi/test_file_system_backend.cc
@@ -32,9 +32,7 @@ class TestFileSystemBackend::QuotaUtil
   QuotaUtil(base::SequencedTaskRunner* task_runner)
       : usage_(0),
         task_runner_(task_runner) {
-    UpdateObserverList::Source source;
-    source.AddObserver(this, task_runner_.get());
-    update_observers_ = UpdateObserverList(source);
+    update_observers_ = update_observers_.AddObserver(this, task_runner_.get());
   }
   virtual ~QuotaUtil() {}
 
@@ -90,9 +88,7 @@ class TestFileSystemBackend::QuotaUtil
       FileSystemType type,
       FileChangeObserver* observer,
       base::SequencedTaskRunner* task_runner) OVERRIDE {
-    ChangeObserverList::Source source = change_observers_.source();
-    source.AddObserver(observer, task_runner);
-    change_observers_ = ChangeObserverList(source);
+    change_observers_ = change_observers_.AddObserver(observer, task_runner);
   }
 
   virtual void AddFileAccessObserver(