MD History: update (instead of re-create) data sources on sign in change

content/public/browser/web_ui_data_source.h

Index: content/public/browser/web_ui_data_source.h
diff --git a/content/public/browser/web_ui_data_source.h b/content/public/browser/web_ui_data_source.h
index 5c278c5069feef7d60c6a1d02d061f78350f76c1..c5104d159d1a095cbe0bc48667d2ad2f1c835b50 100644
--- a/content/public/browser/web_ui_data_source.h
+++ b/content/public/browser/web_ui_data_source.h
@@ -7,6 +7,8 @@
 
 #include <stdint.h>
 

[Charlie Reis, 2016/11/16 18:38:46]

nit: No blank line?

+#include <memory>
+
 #include "base/callback.h"
 #include "base/strings/string16.h"
 #include "content/common/content_export.h"
@@ -27,10 +29,18 @@ class WebUIDataSource {
 
   CONTENT_EXPORT static WebUIDataSource* Create(const std::string& source_name);
 
-  // Adds a WebUI data source to |browser_context|.
+  // Adds a WebUI data source to |browser_context|. TODO(dbeam): update this API
+  // to take a std::unique_ptr instead to make it clear that |source| can be
+  // destroyed and references should not be kept by callers. Use |Update()|
+  // if you need to change an existing data source.
   CONTENT_EXPORT static void Add(BrowserContext* browser_context,
                                  WebUIDataSource* source);
 
+  CONTENT_EXPORT static void Update(

[Charlie Reis, 2016/11/16 18:38:46]

Please include comments for all methods in the public interface.  (It's probably
worth also explaining why some cases should use Update rather than Add, given
the bug it's fixing.)

+      BrowserContext* browser_context,
+      const std::string& source_name,
+      std::unique_ptr<base::DictionaryValue> update);
+
   // Adds a string keyed to its name to our dictionary.
   virtual void AddString(const std::string& name,
                          const base::string16& value) = 0;