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Previously the blink accepts only native files as a result value of the file
chooser. The information is conveyed to the FileInputType. Then FileInputType
generates the File class instances from the information, and the instances are
used to compose the form request.

Thic CL adds non-native file support to the above code path.

* Adds noo-native file information (file system URL and metadata) to structures
  representing selected file (FileChooserFileInfo, SelectedFileInfo).

* When FileInputType generates the File class instances, let the class refer the
  non-native file information.

* When FileInputType checks the change of selected files, let the class refer
  the non-native file information.

BUG=126902
TEST=None

Review URL: https://codereview.chromium.org/640723006

git-svn-id: svn://svn.chromium.org/blink/trunk@183960 bbb929c8-8fbe-4397-9dbb-9b2b20218538