[ImportantSites] Adding usage metrics.

chrome/android/java/src/org/chromium/chrome/browser/preferences/privacy/ClearBrowsingDataPreferences.java

Index: chrome/android/java/src/org/chromium/chrome/browser/preferences/privacy/ClearBrowsingDataPreferences.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/preferences/privacy/ClearBrowsingDataPreferences.java b/chrome/android/java/src/org/chromium/chrome/browser/preferences/privacy/ClearBrowsingDataPreferences.java
index ae0ad9c391d31a3321fad1a0a5dab00048ca8ebd..2145fb3a63178398541ed3d0d42eeb73f7497625 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/preferences/privacy/ClearBrowsingDataPreferences.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/preferences/privacy/ClearBrowsingDataPreferences.java
@@ -15,6 +15,7 @@ import android.widget.ListView;
 
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.metrics.RecordHistogram;
+import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.BrowsingDataType;
 import org.chromium.chrome.browser.ChromeFeatureList;
@@ -213,6 +214,8 @@ public class ClearBrowsingDataPreferences extends PreferenceFragment
     private ProgressDialog mProgressDialog;
     private Item[] mItems;
 
+    // This is a constant on the C++ side.
+    private int mMaxImportantSites;
     // This is the sorted list of important registerable domains. If null, then we haven't finished
     // fetching them yet.
     private String[] mSortedImportantDomains;
@@ -344,11 +347,17 @@ public class ClearBrowsingDataPreferences extends PreferenceFragment
      * </ol>
      */
     private boolean shouldShowImportantSitesDialog() {
-        if (mSortedImportantDomains == null || mSortedImportantDomains.length == 0) return false;
+        if (!ChromeFeatureList.isEnabled(ChromeFeatureList.IMPORTANT_SITES_IN_CBD)) return false;
         EnumSet<DialogOption> selectedOptions = getSelectedOptions();
-        return ChromeFeatureList.isEnabled(ChromeFeatureList.IMPORTANT_SITES_IN_CBD)
-                && (selectedOptions.contains(DialogOption.CLEAR_CACHE)
-                           || selectedOptions.contains(DialogOption.CLEAR_COOKIES_AND_SITE_DATA));
+        if (!selectedOptions.contains(DialogOption.CLEAR_CACHE)
+                && !selectedOptions.contains(DialogOption.CLEAR_COOKIES_AND_SITE_DATA)) {
+            return false;
+        }
+        boolean haveImportantSites =
+                mSortedImportantDomains != null && mSortedImportantDomains.length != 0;
+        RecordHistogram.recordBooleanHistogram(
+                "History.ClearBrowsingData.ImportantDialogShown", haveImportantSites);
+        return haveImportantSites;
     }
 
     @Override
@@ -395,6 +404,8 @@ public class ClearBrowsingDataPreferences extends PreferenceFragment
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        RecordUserAction.record("ClearBrowsingData_DialogCreated");
+        mMaxImportantSites = PrefServiceBridge.getMaxImportantSites();
         PrefServiceBridge.getInstance().requestInfoAboutOtherFormsOfBrowsingHistory(this);
         getActivity().setTitle(R.string.clear_browsing_data_title);
         addPreferencesFromResource(R.xml.clear_browsing_data_preferences);
@@ -565,6 +576,10 @@ public class ClearBrowsingDataPreferences extends PreferenceFragment
 
     @Override
     public void onImportantRegisterableDomainsReady(String[] domains, String[] exampleOrigins) {
+        // mMaxImportantSites is a constant on the C++ side.
+        int domainLength = domains != null ? domains.length : 0;
+        RecordHistogram.recordCustomCountHistogram("History.ClearBrowsingData.NumImportant",
+                domainLength, 0, mMaxImportantSites + 1, mMaxImportantSites + 1);
         mSortedImportantDomains = Arrays.copyOf(domains, domains.length);
         mSortedExampleOrigins = Arrays.copyOf(exampleOrigins, exampleOrigins.length);
     }
@@ -579,6 +594,14 @@ public class ClearBrowsingDataPreferences extends PreferenceFragment
             // Deselected means that the user is excluding the domain from being cleared.
             String[] deselectedDomains = data.getStringArrayExtra(
                     ConfirmImportantSitesDialogFragment.DESELECTED_DOMAINS_TAG);
+            int deselectedLength = deselectedDomains != null ? deselectedDomains.length : 0;
+            // mMaxImportantSites is a constant on the C++ side.
+            RecordHistogram.recordCustomCountHistogram(
+                    "History.ClearBrowsingData.ImportantDeselectedNum", deselectedLength, 0,
+                    mMaxImportantSites + 1, mMaxImportantSites + 1);
+            RecordHistogram.recordPercentageHistogram(
+                    "History.ClearBrowsingData.ImportantDeselectedPercent",
+                    deselectedDomains.length * 100 / mSortedImportantDomains.length);

[Mark P, 2016/06/30 05:29:09]

I'm a little confused by what you're doing here.  Why are you dividing by
mSortedImportantDomains?  The code and description earlier implies that the
number of sites you showed the user is at most mMaxImportantSites == 3, or more
precisely domains.length.  Am I wrong?

[dmurph, 2016/06/30 20:16:29]

Here we want to figure out the percent of sites that were deselected, based on
the number we showed to the user (as we could be showing less than the max).

             clearBrowsingData(getSelectedOptions(), deselectedDomains);
         }
     }