Ntp: restore scroll position.

content/public/browser/navigation_entry.h

Index: content/public/browser/navigation_entry.h
diff --git a/content/public/browser/navigation_entry.h b/content/public/browser/navigation_entry.h
index 87c17cd29e18c2dd566e6435cc46dbb6716c75d5..23a9f1f01542c81f7c37780ab5e83043b06819a0 100644
--- a/content/public/browser/navigation_entry.h
+++ b/content/public/browser/navigation_entry.h
@@ -7,6 +7,7 @@
 
 #include <stdint.h>
 
+#include <map>
 #include <memory>
 #include <string>
 
@@ -205,6 +206,8 @@ class NavigationEntry {
   // If present, fills the |data| present at the specified |key|.
   virtual bool GetExtraData(const std::string& key,
                             base::string16* data) const = 0;
+  // Returns the extra data for this entry.
+  virtual const std::map<std::string, base::string16>& GetExtraData() const = 0;

[clamy, 2016/09/19 09:49:23]

I cannot see any usage outside of content/ of this function. The content/ public
API policy is not to expose any function that is not used outside of content/.
So this should be removed.

Additionally, why do you need to expose the map when you have getters and
setters to interact with it?

[Michael van Ouwerkerk, 2016/09/19 14:27:40]

Hi, are you suggesting that I should move this method to NavigationEntryImpl to
avoid defining it in the public content API? CreateJavaNavigationEntry in
navigation_controller_android.cc would then have to cast from NavigationEntry to
NavigationEntryImpl. That would feel like a strange design to me.

I need this method because CreateJavaNavigationEntry makes a Java copy of the
entry, and it does not know what the keys are.

[clamy, 2016/09/19 15:25:27]

Yes precisely. This is the design used all over content: anything not needed
outside of content/ is defined in the impl version of the class. Then classes
inside content/ freely use the impl version. This is done either by casting to
the FooImpl version or by having the implementation of functions of the public
API return the Imp version. Example:

NavigationEntry NavigationController::GetEntryAtIndex
is actually implemented as
NavigationEntryImpl NavigationControllerImpl::GetEntryAsIndex (in
navigation_controller_impl.h). For your use case, NavigationControllerAndroid
should just ensured it's keeping a pointer to a NavigationControllerImpl, and
then all NavigationEntries returned by this controller can be directly used a
NavigationEntryImpls.

Alternatively, you can safely cast the NavigationEntry to a NavigationEntryImpl.
Acknowledged.

[Michael van Ouwerkerk, 2016/09/19 15:57:39]

Done.

   // Removes the data at the specified |key|.
   virtual void ClearExtraData(const std::string& key) = 0;