Expose method to reset translate settings.

ios/web_view/public/cwv_translation_controller.h

Index: ios/web_view/public/cwv_translation_controller.h
diff --git a/ios/web_view/public/cwv_translation_controller.h b/ios/web_view/public/cwv_translation_controller.h
index ee3106649081725778d7c3999c2ca9b73fe042d1..1dce60ca2c22b0e89c96071f312938f4cb24401e 100644
--- a/ios/web_view/public/cwv_translation_controller.h
+++ b/ios/web_view/public/cwv_translation_controller.h
@@ -52,6 +52,10 @@ CWV_EXPORT
 @property(nonatomic, readonly)
     NSSet<CWVTranslationLanguage*>* supportedLanguages;
 
+// Resets all translation policies to CWVTranslationPolicyAsk.
+// Only resets non-incognito settings.
++ (void)resetTranslationPolicies;
+
 // Begins translation on the current page from |sourceLanguage| to
 // |targetLanguage|. These language parameters must be chosen from
 // |supportedLanguages|. Set |userInitiated| to YES if translation
@@ -70,6 +74,7 @@ CWV_EXPORT
 
 // Sets or retrieves translation policies associated with a specified language.
 // |pageLanguage| should be the language code of the language.
+// Asserts in incognito mode.

[Hiroshi Ichikawa, 2017/07/10 06:22:26]

Should be "Causes assertion failure in incognito mode", or maybe you can just
say "Not supported in incognito mode".

The current sentence can be read as "Asserts that it is in incognito mode" which
means opposite.

[Eugene But (OOO till 7-30), 2017/07/10 16:17:43]

What is the value of asserting in Incognito mode? If apps want to be able to set
policies in incognito mode we should allow that in API. I think it should be up
to application developer to decide whether or not they want to allow translation
policies for Incognito. WDYT?

[jzw1, 2017/07/10 18:51:40]

I think it makes sense to not share translate preferences between incognito and
non-incognito, even though Chrome iOS shares them. If we want to go with Chrome
iOS route, we'd have to refactor browser states to have a parent child
relationship between non-incognito and incognito browser states.

I'd want to discourage setting policies for incognito because they are only
stored in-memory, and I don't really see value in letting users store temporary
values.

 - (void)setTranslationPolicy:(CWVTranslationPolicy*)policy
              forPageLanguage:(CWVTranslationLanguage*)pageLanguage;
 - (CWVTranslationPolicy*)translationPolicyForPageLanguage:
@@ -77,6 +82,7 @@ CWV_EXPORT
 
 // Sets or retrieves translation policies associated with a specified page.
 // |pageHost| should be the hostname of the website. Must not be empty.
+// Asserts in incognito mode.

[Hiroshi Ichikawa, 2017/07/10 06:22:26]

Ditto.

[jzw1, 2017/07/10 18:51:40]

Done.

 - (void)setTranslationPolicy:(CWVTranslationPolicy*)policy
                  forPageHost:(NSString*)pageHost;
 - (CWVTranslationPolicy*)translationPolicyForPageHost:(NSString*)pageHost;