Make the file chooser use PP_ArrayOutput

ppapi/shared_impl/array_writer.h

Index: ppapi/shared_impl/array_writer.h
diff --git a/ppapi/shared_impl/array_writer.h b/ppapi/shared_impl/array_writer.h
new file mode 100644
index 0000000000000000000000000000000000000000..cabd0af905efc10cf89de0dfffcffe45da30433c
--- /dev/null
+++ b/ppapi/shared_impl/array_writer.h
@@ -0,0 +1,98 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PPAPI_SHARED_IMPL_ARRAY_WRITER_H_
+#define PPAPI_SHARED_IMPL_ARRAY_WRITER_H_
+
+#include <string.h>
+
+#include <vector>
+
+#include "base/memory/ref_counted.h"
+#include "ppapi/c/pp_array_output.h"
+#include "ppapi/c/pp_resource.h"
+#include "ppapi/c/pp_var.h"
+#include "ppapi/shared_impl/ppapi_shared_export.h"
+
+namespace ppapi {
+
+class Resource;
+
+// Holds a PP_ArrayWriter and provides helper functions for writing arrays
+// to it. It also handles 0-initialization of the raw C struct and attempts
+// to prevent you from writing the array twice.
+class PPAPI_SHARED_EXPORT ArrayWriter {
+ public:
+  ArrayWriter();  // Creates an is_null() object
+  ArrayWriter(const PP_ArrayOutput& output);
+  ~ArrayWriter();
+
+  bool is_valid() const { return !!pp_array_output_.GetDataBuffer; }
+  bool is_null() const { return !is_valid(); }
+
+  void set_pp_array_output(const PP_ArrayOutput& output) {
+    pp_array_output_ = output;
+  }
+
+  // Sets the array output back to its is_null() state.
+  void Reset();
+
+  // Copies the given vector of data to the plugin output array.
+  //
+  // Returns true on success, false if the plugin reported allocation failure.
+  // In either case, the object will become is_null() immediately after the
+  // call since one output function should only be issued once.
+  //
+  // THIS IS DESIGNED FOR POD ONLY. For the case of resources, for example, we
+  // want to transfer a reference only on success. Likewise, if you have a
+  // structure of PP_Vars or a struct that contains a PP_Resource, we need to
+  // make sure that the right thing happens with the ref on success and failure.
+  template<typename T>
+  bool StoreVector(const std::vector<T>& input) {
+    // Always call the alloc function, even on 0 array size.
+    void* dest = pp_array_output_.GetDataBuffer(
+        pp_array_output_.user_data,
+        static_cast<uint32_t>(input.size()),
+        sizeof(T));
+
+    // Regardless of success, we clear the output to prevent future calls on
+    // this same output object.
+    Reset();
+
+    if (input.empty())
+      return true;  // Allow plugin to return NULL on 0 elements.
+    if (!dest)
+      return false;
+
+    memcpy(dest, &input[0], sizeof(T) * input.size());
+    return true;
+  }
+
+  // Stores the given vector of resources as PP_Resources to the output vector,
+  // adding one reference to each.
+  //
+  // On failure this returns false, nothing will be copied, and the resource
+  // refcounts will be unchanged. In either case, the object will become
+  // is_null() immediately after the call since one output function should only
+  // be issued once.
+  //
+  // Note: potentially this could be a template in case you have a vector of
+  // FileRef objects, for example. However, this saves code since there's only
+  // one instantiation and is sufficient for now.
+  bool StoreResourceVector(
+      const std::vector< scoped_refptr<Resource> >& input);
+
+  // Like the above version but takes an array of AddRed'ed PP_Resources. On
+  // storage failure, this will release each resource.
+  bool StoreResourceVector(const std::vector<PP_Resource>& input);
+
+ private:
+  PP_ArrayOutput pp_array_output_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArrayWriter);
+};
+
+}  // namespace ppapi
+
+#endif  // PPAPI_SHARED_IMPL_ARRAY_WRITER_H_