iOS: cd into Documents folder at startup

CQ_INCLUDE_TRYBOTS=skia.primary:Test-iOS-Clang-iPadMini4-GPU-GX6450-arm-Release

Change-Id: I7beadad742bc9444491c7a315a827297a636d70d
Reviewed-on: https://skia-review.googlesource.com/8049
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 6dc1bd9..e371bbc 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -32,6 +32,7 @@
 #include "SkThreadUtils.h"
 #include "Test.h"
 #include "Timer.h"
+#include "ios_utils.h"
 #include "picture_utils.h"
 #include "sk_tool_utils.h"
 #include "SkScan.h"
@@ -1284,6 +1285,9 @@
 
 int dm_main();
 int dm_main() {
+#if defined(SK_BUILD_FOR_IOS)
+    cd_Documents();
+#endif
     setbuf(stdout, nullptr);
     setup_crash_handler();