Added support for ext4 ASEC resizing.

ASECs formatted as ext4 can now be resized using vdc asec resize.
Refactored some common code.
Requires resize2fs.

Change-Id: Ie78bb6015114a7bc4af42b16d1f299322ffc1e2a
Signed-off-by: Daniel Rosenberg <drosen@google.com>
diff --git a/Ext4.h b/Ext4.h
index 54fbec3..c768f5a 100644
--- a/Ext4.h
+++ b/Ext4.h
@@ -24,6 +24,7 @@
     static int doMount(const char *fsPath, const char *mountPoint, bool ro, bool remount,
             bool executable);
     static int format(const char *fsPath, unsigned int numSectors, const char *mountpoint);
+    static int resize(const char *fsPath, unsigned int numSectors);
 };
 
 #endif