Added translation policy API.

components/translate/core/browser/translate_ui_delegate.h

Index: components/translate/core/browser/translate_ui_delegate.h
diff --git a/components/translate/core/browser/translate_ui_delegate.h b/components/translate/core/browser/translate_ui_delegate.h
index 230a68cd6c973319c5dc5c44c80408990aae1294..7242830cf1fa65e92f7606fa50e64b8c6c7e1d2f 100644
--- a/components/translate/core/browser/translate_ui_delegate.h
+++ b/components/translate/core/browser/translate_ui_delegate.h
@@ -77,6 +77,9 @@ class TranslateUIDelegate {
   // Returns the ISO code for the language at |index|.
   std::string GetLanguageCodeAt(size_t index) const;
 
+  // Returns the index of |language_code|.
+  size_t GetLanguageIndex(const std::string& language_code);
+
   // Returns the displayable name for the language at |index|.
   base::string16 GetLanguageNameAt(size_t index) const;
 
@@ -101,23 +104,49 @@ class TranslateUIDelegate {
   // Returns true if the current language is blocked.
   bool IsLanguageBlocked();
 
+  // Returns true if |language_code| is blocked.
+  bool IsLanguageBlocked(const std::string& language_code);
+
   // Sets the value if the current language is blocked.
   void SetLanguageBlocked(bool value);
 
+  // Sets the value if the |language_code| is blocked.
+  void SetLanguageBlocked(bool value, const std::string& language_code);

[Hiroshi Ichikawa, 2017/05/10 08:36:55]

Optional: I slightly prefer the opposite order of parameters: language_code,
value. I believe setter for key-value pairs are usually in (key, value) order.

[jzw1, 2017/05/11 03:03:17]

I kind of like this order since I'm overloading the method above it. If someone
else feels strongly about this I'll change it.

+
   // Returns true if the current webpage is blacklisted.
   bool IsSiteBlacklisted();
 
+  // Returns true if |page_host| is blacklisted.
+  bool IsSiteBlacklisted(const std::string& page_host);
+
   // Sets the value if the current webpage is blacklisted.
   void SetSiteBlacklist(bool value);
 
+  // Sets the value if the |page_host| is blacklisted.
+  void SetSiteBlacklist(bool value, const std::string& page_host);
+
   // Returns true if the webpage in the current original language should be
   // translated into the current target language automatically.
   bool ShouldAlwaysTranslate();
 
+  // Returns true if the webpage in the |from_language| should be
+  // translated into the |to_language| automatically.
+  bool ShouldAlwaysTranslate(const std::string& from_language,

[Hiroshi Ichikawa, 2017/05/10 08:36:55]

Is this method used? Looks sufficient with only GetAlwaysTranslateToLanguage().

[jzw1, 2017/05/11 03:03:17]

Done.

+                             const std::string& to_language);
+
   // Sets the value if the webpage in the current original language should be
   // translated into the current target language automatically.
   void SetAlwaysTranslate(bool value);
 
+  // Sets the value if the webpage in the |from_language| should be
+  // translated into the |to_language| automatically.
+  void SetAlwaysTranslate(bool value,

[Hiroshi Ichikawa, 2017/05/10 08:36:55]

This API looks a bit weird. This API seems to indicate that you can set a
boolean value for each (from_language, to_language) pair. But it doesn't make
sense to e.g.,

SetAlwaysTranslate(true, "en", "ja");
SetAlwaysTranslate(true, "en", "ko");

Instead, how about defining:

void EnableToAlwaysTranslate(const std::string& from_language, const
std::string& to_language);
void DisableToAlwaysTranslate(const std::string& from_language);

Or maybe only the former method, and let it disable always-translate when
to_language is empty.

[jzw1, 2017/05/11 03:03:17]

Wouldn't you still be able to do something like:
EnableAlwaysTranslate("en", "ja");
EnableAlwaysTranslate("en", "ko");

How about I add a comment that the last pair wins?

[Hiroshi Ichikawa, 2017/05/11 04:14:15]

My point is rather that having a boolean parameter for this method is wierd. If
|value| is false, |to_language| is ignored, right? That's why I feel this API is
more natural:

void EnableToAlwaysTranslate(const std::string& from_language, const
std::string& to_language);
void DisableToAlwaysTranslate(const std::string& from_language);

In this API, it's obvious that |to_language| is not necessary when you disable
it.

But if you document the behavior in detail, the current API would be acceptable
too.

[jzw1, 2017/05/11 04:42:59]

I'll just update the comment. 

+                          const std::string& from_language,
+                          const std::string& to_language);
+
+  // Returns the language to always translate |from_language| to.

[Hiroshi Ichikawa, 2017/05/10 08:36:55]

Can you document the return value in case |from_language| is not set as a
language to always translate?

[jzw1, 2017/05/11 03:03:17]

Done.

+  std::string GetAlwaysTranslateToLanguage(const std::string& from_language);
+
   // Returns true if the Always Translate checkbox should be checked by default.
   bool ShouldAlwaysTranslateBeCheckedByDefault();