[FileAPI] Check Platform availability before using it in LocalFileSystem

Source/modules/filesystem/LocalFileSystem.h

Index: Source/modules/filesystem/LocalFileSystem.h
diff --git a/Source/modules/filesystem/LocalFileSystem.h b/Source/modules/filesystem/LocalFileSystem.h
index f7190cf45157447b7658c258e677085047465fa4..316731b8985388b1c98061706934fa6c990ae02e 100644
--- a/Source/modules/filesystem/LocalFileSystem.h
+++ b/Source/modules/filesystem/LocalFileSystem.h
@@ -44,6 +44,7 @@ class FileSystemClient;
 class ExecutionContext;
 class KURL;
 class LocalFrame;
+class WebFileSystem;
 
 class LocalFileSystem FINAL : public NoBaseWillBeGarbageCollectedFinalized<LocalFileSystem>, public WillBeHeapSupplement<LocalFrame>, public WillBeHeapSupplement<WorkerClients> {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(LocalFileSystem);
@@ -71,10 +72,12 @@ protected:
     explicit LocalFileSystem(PassOwnPtr<FileSystemClient>);
 
 private:
+    WebFileSystem* fileSystem() const;
     void requestFileSystemAccessInternal(ExecutionContext*, const Closure& allowed, const Closure& denied);
+    void fileSystemNotAvailable(PassRefPtrWillBeRawPtr<ExecutionContext>, PassRefPtr<CallbackWrapper>);
     void fileSystemNotAllowedInternal(PassRefPtrWillBeRawPtr<ExecutionContext>, PassRefPtr<CallbackWrapper>);
     void fileSystemAllowedInternal(PassRefPtrWillBeRawPtr<ExecutionContext>, FileSystemType, PassRefPtr<CallbackWrapper>);
-    void resolveURLInternal(const KURL&, PassRefPtr<CallbackWrapper>);
+    void resolveURLInternal(PassRefPtrWillBeRawPtr<ExecutionContext>, const KURL&, PassRefPtr<CallbackWrapper>);
     void deleteFileSystemInternal(PassRefPtrWillBeRawPtr<ExecutionContext>, FileSystemType, PassRefPtr<CallbackWrapper>);
     OwnPtr<FileSystemClient> m_client;
 };