Make sure Usage category heading goes away when we clear local data.

chrome/android/java/src/org/chromium/chrome/browser/preferences/website/SingleWebsitePreferences.java

Index: chrome/android/java/src/org/chromium/chrome/browser/preferences/website/SingleWebsitePreferences.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/preferences/website/SingleWebsitePreferences.java b/chrome/android/java/src/org/chromium/chrome/browser/preferences/website/SingleWebsitePreferences.java
index eef6388a86a0f1caf2547070b3b9da9c83a76a11..1661a199fdbd62be0eb343b4f7ac914f9d4eb791 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/preferences/website/SingleWebsitePreferences.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/preferences/website/SingleWebsitePreferences.java
@@ -384,8 +384,13 @@ public class SingleWebsitePreferences extends PreferenceFragment
                 new Website.StoredDataClearedCallback() {
                     @Override
                     public void onStoredDataCleared() {
-                        getPreferenceScreen().removePreference(
-                                getPreferenceScreen().findPreference(PREF_CLEAR_DATA));
+                        PreferenceScreen preferenceScreen = getPreferenceScreen();
+                        preferenceScreen.removePreference(
+                                preferenceScreen.findPreference(PREF_CLEAR_DATA));
+                        if (!hasUsagePreferences()) {

[newt (away), 2015/02/27 19:26:44]

Instead of hasUsagePreferences(), I'd directly check if the usage pref is
present:

    Preference usage = preferenceScreen.findPreference(PREF_USAGE)
    if (usage != null) preferenceScreen.removePreference(usage);

That seems safer in case the implementation of hasUsagePreferences() were to
change (e.g. to check whether it *should* have a usage pref, which at this point
would return false).

[Finnur, 2015/03/02 09:18:47]

I think there's a bit of a misunderstanding here...

The code is doing the equivalent of:

RemoveClearDataPref();
if (NoMorePrefsUnderUsageCategory())
  RemoveUsageCategory();

What you are proposing is:

RemoveClearDataPref();
if (UsageCategoryVisible())
  RemoveUsageCategory();

That code would be correct today (since the Usage category currently only
contains one pref), but would break if we add a new ones...

Since I'm pretty sure this is correct as-is (and I'm on a different timezone),
I'll check in but am more than willing to do a followup CL if the conclusion of
this discussion is different than I expect.

[newt (away), 2015/03/02 19:14:04]

Ah, my bad. I wasn't making the correct distinction between the usage category
title and the single item in that category ("clear data").

+                            preferenceScreen.removePreference(
+                                    preferenceScreen.findPreference(PREF_USAGE));
+                        }
                         popBackIfNoSettings();
                     }
                 });