Enable Oilpan by default in modules/filesystem/

Source/modules/filesystem/DirectoryReader.cpp

Index: Source/modules/filesystem/DirectoryReader.cpp
diff --git a/Source/modules/filesystem/DirectoryReader.cpp b/Source/modules/filesystem/DirectoryReader.cpp
index 82658353904e33e73972256a15dfe38926d3fbd9..7bf5fdd9df1b0c7180a3f79a6da8cf287daeffda 100644
--- a/Source/modules/filesystem/DirectoryReader.cpp
+++ b/Source/modules/filesystem/DirectoryReader.cpp
@@ -40,7 +40,7 @@ namespace WebCore {
 
 class DirectoryReader::EntriesCallbackHelper : public EntriesCallback {
 public:
-    EntriesCallbackHelper(PassRefPtrWillBeRawPtr<DirectoryReader> reader)
+    EntriesCallbackHelper(DirectoryReader* reader)

[haraken, 2014/06/07 08:11:04]

Add explicit.

[sof, 2014/06/07 13:18:53]

Done.

         : m_reader(reader)
     {
     }
@@ -51,13 +51,13 @@ public:
     }
 
 private:
-    // FIXME: This RefPtr keeps the reader alive until all of the readDirectory results are received. crbug.com/350285
-    RefPtrWillBePersistent<DirectoryReader> m_reader;
+    // FIXME: This Persistent keeps the reader alive until all of the readDirectory results are received. crbug.com/350285
+    Persistent<DirectoryReader> m_reader;
 };
 
 class DirectoryReader::ErrorCallbackHelper : public ErrorCallback {
 public:
-    ErrorCallbackHelper(PassRefPtrWillBeRawPtr<DirectoryReader> reader)
+    ErrorCallbackHelper(DirectoryReader* reader)

[haraken, 2014/06/07 08:11:04]

Add explicit.

[sof, 2014/06/07 13:18:53]

Done.

         : m_reader(reader)
     {
     }
@@ -68,10 +68,10 @@ public:
     }
 
 private:
-    RefPtrWillBePersistent<DirectoryReader> m_reader;
+    Persistent<DirectoryReader> m_reader;
 };
 
-DirectoryReader::DirectoryReader(PassRefPtrWillBeRawPtr<DOMFileSystemBase> fileSystem, const String& fullPath)
+DirectoryReader::DirectoryReader(DOMFileSystemBase* fileSystem, const String& fullPath)
     : DirectoryReaderBase(fileSystem, fullPath)
     , m_isReading(false)
 {
@@ -90,7 +90,7 @@ void DirectoryReader::readEntries(PassOwnPtr<EntriesCallback> entriesCallback, P
     }
 
     if (m_error) {
-        filesystem()->scheduleCallback(errorCallback, m_error.get());
+        filesystem()->scheduleCallback(errorCallback, PassRefPtrWillBeRawPtr<FileError>(m_error.get()));

[haraken, 2014/06/07 08:11:04]

I'm curious why this can't be just 'm_error'.

[sof, 2014/06/07 13:18:53]

Let's see. scheduleCallback() has three function template:

 static void scheduleCallback(ExecutionContext*,PassOwnPtr<CB>,
PassRefWillBeRawPtr<CBArg>);
 static void scheduleCallback(ExecutionContext*,PassOwnPtr<CB>, CBArg*);
 static void scheduleCallback(ExecutionContext*,PassOwnPtr<CB>, const CBArg&);

if we pass m_error (of type RefPtrWillBeMember<FileError>), then in Oilpan mode:

 Member<FileError> matches the 3rd version (as no implicit conversions happen
prior to template matching), with CBArg = Member<FileError>

The function template then instantiates a Task template, which has a call to
handleError(FileError*) within it, e.g., m_callback->handleError(m_error) is
what it expands to.

The implicit conversion "operator T*()" over Member then kicks in and everything
is fine.

For the non-Oilpan case, m_error is of type RefPtr<FileError>, so you end up
with m_callback->handleError(m_error) and ask the compiler to convert a
RefPtr<FileError> to a FileError*. No implicit conversion exist over RefPtr<>
for that, hence compilation failure.

If instead you say, "let's just use m_error.get() then", you will resolve to the
2nd scheduleCallback() version above. This runs into trouble for the non-Oilpan
case, as it keeps the callback argument in a Persistent<> (to support bare
Oilpan pointers), which you cannot put a non-GCed pointer into (FileError.)

Which is why this ends up as PassRefPtrWillBeRawPtr<FileError>(m_error.get()) to
force the use of the first overload. It doesn't work without the .get(), as
there is RawPtr(Member<T>) constructor.

Does that explain things?

[haraken, 2014/06/07 16:45:27]

Thanks for the details, makes sense.

         return;
     }