[NTP Snippets] Clear the snippets when the user signs out

chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsBridge.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsBridge.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsBridge.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsBridge.java
index 384133a92cc473837e0d7891ac514c99580f7353..8d2e523ccf63b2502fc4e6b90cdb1076c4d0c4dd 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsBridge.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsBridge.java
@@ -7,7 +7,6 @@
 import android.graphics.Bitmap;
 
 import org.chromium.base.Callback;
-
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.chrome.browser.profiles.Profile;
 
@@ -36,6 +35,9 @@
      */
     public interface SnippetsObserver {
         void onSnippetsReceived(List<SnippetArticle> snippets);
+
+        /** Called when the service wants to force clear the displayed snippets. */
+        void onSnippetsCleared();
     }
 
     /**
@@ -139,6 +141,15 @@ private void onSnippetsAvailable(String[] ids, String[] titles, String[] urls, S
         mObserver.onSnippetsReceived(newSnippets);
     }
 
+    @CalledByNative
+    private void onSnippetsCleared() {
+     // Don't notify observer if we've already been destroyed.
+        if (mNativeSnippetsBridge == 0) return;

[Bernhard Bauer, 2016/05/17 09:12:48]

If the native side has been destroyed, this wouldn't be called, no? You could
assert that it's non-zero instead.

[dgn, 2016/05/17 10:46:00]

Removed the thing entirely. I'm not quite sure in which conditions we can run
into such a case with onSnippetsAvailable(). I think making
NTPSnippetsBridge::NTPSnippetsServiceLoaded() being called in SetObserver
instead of in the constructor made that impossible.

+        if (mObserver == null) return;
+
+        mObserver.onSnippetsCleared();
+    }
+
     private native long nativeInit(Profile profile);
     private native void nativeDestroy(long nativeNTPSnippetsBridge);
     private static native void nativeFetchSnippets();