Support "full" mode when updating bind mounts of a process.

Bug: 133829348
Test: manual
Test: atest cts/hostsidetests/appsecurity/src/android/appsecurity/cts/ExternalStorageHostTest.java
Change-Id: I5f48ecbfe8cce243fa75a2e8447ce1d4676003ad
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index 637dc47..44bff5a 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -554,6 +554,8 @@
                 storageSource = "/mnt/runtime/read";
             } else if (mode == "write") {
                 storageSource = "/mnt/runtime/write";
+            } else if (mode == "full") {
+                storageSource = "/mnt/runtime/full";
             } else {
                 // Sane default of no storage visible
                 _exit(0);