Ntp: restore scroll position.

chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java b/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
index f97f467908e0ad2af404f8aed63c22a52cd2777b..8f6e65b9873d0ad00bc8ef754f96b426a300f5c8 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
@@ -99,6 +99,7 @@ import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content.browser.crypto.CipherFactory;
 import org.chromium.content_public.browser.GestureStateListener;
 import org.chromium.content_public.browser.LoadUrlParams;
+import org.chromium.content_public.browser.NavigationEntry;
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.content_public.common.Referrer;
 import org.chromium.content_public.common.ResourceRequestBody;
@@ -1435,6 +1436,33 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
     }
 
     /**
+     * Returns the value for the extra data that was stored with {@code key} in the last committed
+     * navigation entry. Returns null if there is no last committed entry, or if no data is found.
+     * @param key The key for the data field.
+     * @return The data value, or null if no data is found.
+     */
+    public String getLastCommittedNavigationEntryExtraData(String key) {
+        if (getWebContents() == null) return null;
+
+        NavigationEntry entry = getWebContents().getNavigationController().getEntryAtIndex(

[Bernhard Bauer, 2016/09/16 15:02:50]

Extract the NavigationController to a local variable?

[Michael van Ouwerkerk, 2016/09/16 16:35:05]

Done.

+                getWebContents().getNavigationController().getLastCommittedEntryIndex());
+        if (entry == null) return null;
+
+        return entry.getExtraData(key);
+    }
+
+    /**
+     * Stores {@code value} under {@code key} in the last committed navigation entry, if such an
+     * entry exists.
+     * @param key The key for the data field.
+     * @param value The value for the data field.
+     */
+    public void setLastCommittedNavigationEntryExtraData(String key, String value) {
+        assert mNativeTabAndroid != 0;
+        nativeSetLastCommittedNavigationEntryExtraData(mNativeTabAndroid, key, value);

[Bernhard Bauer, 2016/09/16 15:02:50]

Would it make sense to move the JNI call to NavigationController so it's a bit
more symmetric with the getter above?

[Michael van Ouwerkerk, 2016/09/16 16:35:05]

Done.

+    }
+
+    /**
      * Replaces the current NativePage with a empty stand-in for a NativePage. This can be used
      * to reduce memory pressure.
      */
@@ -3325,6 +3353,8 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
             long intentReceivedTimestamp, boolean hasUserGesture);
     private native void nativeSetActiveNavigationEntryTitleForUrl(long nativeTabAndroid, String url,
             String title);
+    private native void nativeSetLastCommittedNavigationEntryExtraData(
+            long nativeTabAndroid, String key, String value);
     private native boolean nativePrint(long nativeTabAndroid);
     private native Bitmap nativeGetFavicon(long nativeTabAndroid);
     private native void nativeCreateHistoricalTab(long nativeTabAndroid);