Adds ability for BrowserMainParts::PreEarlyInitialization() to fail

I'm moving some code from PreCreateThreads to PreEarlyInitialization()
that may signal a fail. This adds an error code to indicate that.

I will add a test of this in the chrome side that uses it.

BUG=800357
TEST=none

Change-Id: I735c68a8a7588bf2b99405ab0687315329b3f0d0
Reviewed-on: https://chromium-review.googlesource.com/862964
Reviewed-by: John Abd-El-Malek <[email protected]>
Commit-Queue: Scott Violet <[email protected]>
Cr-Commit-Position: refs/heads/master@{#528970}
diff --git a/chrome/browser/chrome_browser_main.h b/chrome/browser/chrome_browser_main.h
index c6c7fa3..7b00eeb 100644
--- a/chrome/browser/chrome_browser_main.h
+++ b/chrome/browser/chrome_browser_main.h
@@ -59,7 +59,7 @@
   // These are called in-order by content::BrowserMainLoop.
   // Each stage calls the same stages in any ChromeBrowserMainExtraParts added
   // with AddParts() from ChromeContentBrowserClient::CreateBrowserMainParts.
-  void PreEarlyInitialization() override;
+  int PreEarlyInitialization() override;
   void PostEarlyInitialization() override;
   void ToolkitInitialized() override;
   void PreMainMessageLoopStart() override;