mandoline filesystem: add a sqlite3 vfs to proxy filesystem usage.

sql/BUILD.gn

Index: sql/BUILD.gn
diff --git a/sql/BUILD.gn b/sql/BUILD.gn
index f3c44be98e03844a8713623ae9ca564661341253..fdf8c7be96edba0cc4405c652c4d42ac8c29e6e0 100644
--- a/sql/BUILD.gn
+++ b/sql/BUILD.gn
@@ -54,6 +54,17 @@ source_set("test_support") {
   ]
 }
 
+source_set("redirection_header") {
+  # This target exists because we need a way to switch between
+  # "test/sql_test_base.h" and "mojo/sql_test_base.h" at compile time, to allow
+  # us to switch out the gtest vs mojo:apptest frameworks.
+  check_includes = false
+
+  sources = [
+    "correct_sql_test_base.h",
+  ]
+}
+
 test("sql_unittests") {
   sources = [
     "connection_unittest.cc",
@@ -64,6 +75,8 @@ test("sql_unittests") {
     "test/paths.cc",
     "test/paths.h",
     "test/run_all_unittests.cc",
+    "test/sql_test_base.cc",
+    "test/sql_test_base.h",
     "test/sql_test_suite.cc",
     "test/sql_test_suite.h",
     "transaction_unittest.cc",
@@ -74,6 +87,7 @@ test("sql_unittests") {
 
   deps = [
     ":sql",
+    ":redirection_header",
     ":test_support",
     "//base/allocator",
     "//base/test:test_support",