Fix crashes when using translate in incognito by overriding some methods.

ios/web_view/internal/translate/web_view_translate_ranker_factory.cc

Index: ios/web_view/internal/translate/web_view_translate_ranker_factory.cc
diff --git a/ios/web_view/internal/translate/web_view_translate_ranker_factory.cc b/ios/web_view/internal/translate/web_view_translate_ranker_factory.cc
index 8c701968a8f4363484c736e59785cbc177f9c1cb..0fe9936a1860f4d87cfea47ddeb6bcd68af103dc 100644
--- a/ios/web_view/internal/translate/web_view_translate_ranker_factory.cc
+++ b/ios/web_view/internal/translate/web_view_translate_ranker_factory.cc
@@ -53,4 +53,9 @@ WebViewTranslateRankerFactory::BuildServiceInstanceFor(
   return std::move(ranker);
 }
 
+web::BrowserState* WebViewTranslateRankerFactory::GetBrowserStateToUse(
+    web::BrowserState* context) const {
+  return context;

[Hiroshi Ichikawa, 2017/07/07 05:15:21]

Can you add a comment explaining that this class overrides this function here to
make this class available in incognito mode too? I was confused why this is
needed until I read the definition of
BrowserStateKeyedServiceFactory::GetBrowserStateToUse().

[jzw1, 2017/07/07 06:20:44]

Done.

+}
+
 }  // namespace ios_web_view