mojo: Improve crash stack.

mojo/runner/host/child_process.cc

Index: mojo/runner/host/child_process.cc
diff --git a/mojo/runner/host/child_process.cc b/mojo/runner/host/child_process.cc
index f0bfd21bedaca18aa6a81f9002b3db8e64852769..0dd6d84c316a7e6d79540384ba497614ad9157a7 100644
--- a/mojo/runner/host/child_process.cc
+++ b/mojo/runner/host/child_process.cc
@@ -8,6 +8,7 @@
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
+#include "base/debug/stack_trace.h"
 #include "base/files/file_path.h"
 #include "base/i18n/icu_util.h"
 #include "base/location.h"
@@ -359,13 +360,18 @@ int ChildProcessMain() {
   // Load the application library before we engage the sandbox.
   app_library = mojo::runner::LoadNativeApplication(
       command_line.GetSwitchValuePath(switches::kChildProcess));
-
   base::i18n::InitializeICU();
   if (app_library)
     CallLibraryEarlyInitialization(app_library);
 #if defined(OS_LINUX) && !defined(OS_ANDROID)
-  if (command_line.HasSwitch(switches::kEnableSandbox))
+  if (command_line.HasSwitch(switches::kEnableSandbox)) {
+#if !defined(OFFICIAL_BUILD)
+    // Initialize stack dumping just before initializing sandbox to make
+    // sure symbol names in all loaded libraries will be cached.
+    base::debug::EnableInProcessStackDumping();
+#endif
     sandbox = InitializeSandbox();
+  }
 #endif
 
   embedder::ScopedPlatformHandle platform_channel =