Add info string to advanced battery usage page

This CL adds an FYI string under the battery graph to let users
know that their current estimate is coming from the enhanced
estimate provider when it is enabled.

Test: Robotests
Bug: 38399654
Change-Id: If5cd622ef0251a5a483cef870fc2261369e14845

src/com/android/settings/fuelgauge/BatteryHistoryPreference.java

@@ -21,6 +21,7 @@ import android.support.annotation.VisibleForTesting;
 import android.support.v7.preference.Preference;
 import android.support.v7.preference.PreferenceViewHolder;
 import android.util.AttributeSet;
+import android.view.View;
 import android.widget.TextView;
 import com.android.internal.os.BatteryStatsHelper;
 import com.android.settings.R;
@@ -32,6 +33,10 @@ import com.android.settings.graph.UsageView;
  */
 public class BatteryHistoryPreference extends Preference {
 
+    private CharSequence mSummary;
+    private TextView mSummaryView;
+    private boolean hideSummary;
+
     @VisibleForTesting
     BatteryInfo mBatteryInfo;
 
@@ -48,6 +53,20 @@ public class BatteryHistoryPreference extends Preference {
         }, batteryStats.getStats(), false);
     }
 
+    public void setBottomSummary(CharSequence text) {
+        mSummary = text;
+        if (mSummaryView != null) {
+            mSummaryView.setText(mSummary);
+        }
+    }
+
+    public void hideBottomSummary() {
+        if (mSummaryView != null) {
+            mSummaryView.setVisibility(View.GONE);
+        }
+        hideSummary = true;
+    }
+
     @Override
     public void onBindViewHolder(PreferenceViewHolder view) {
         super.onBindViewHolder(view);
@@ -56,6 +75,13 @@ public class BatteryHistoryPreference extends Preference {
         }
 
         ((TextView) view.findViewById(R.id.charge)).setText(mBatteryInfo.batteryPercentString);
+        mSummaryView = (TextView) view.findViewById(R.id.bottom_summary);
+        if (mSummary != null) {
+            mSummaryView.setText(mSummary);
+        }
+        if (hideSummary) {
+            mSummaryView.setVisibility(View.GONE);
+        }
         UsageView usageView = (UsageView) view.findViewById(R.id.battery_usage);
         usageView.findViewById(R.id.label_group).setAlpha(.7f);
         mBatteryInfo.bindHistory(usageView);

src/com/android/settings/fuelgauge/PowerUsageAdvanced.java

@@ -69,9 +69,9 @@ public class PowerUsageAdvanced extends PowerUsageBase {
             UsageType.UNACCOUNTED,
             UsageType.OVERCOUNTED};
 
+    @VisibleForTesting BatteryHistoryPreference mHistPref;
+    @VisibleForTesting PreferenceGroup mUsageListGroup;
     private BatteryUtils mBatteryUtils;
-    private BatteryHistoryPreference mHistPref;
-    private PreferenceGroup mUsageListGroup;
     private PowerUsageFeatureProvider mPowerUsageFeatureProvider;
     private PackageManager mPackageManager;
     private UserManager mUserManager;
@@ -170,6 +170,14 @@ public class PowerUsageAdvanced extends PowerUsageBase {
         }
         updatePreference(mHistPref);
         refreshPowerUsageDataList(mStatsHelper, mUsageListGroup);
+
+        if (mPowerUsageFeatureProvider.isEnhancedBatteryPredictionEnabled(context)) {
+            mHistPref.setBottomSummary(
+                    mPowerUsageFeatureProvider.getAdvancedUsageScreenInfoString());
+        } else {
+            mHistPref.hideBottomSummary();
+        }
+
         BatteryEntry.startRequestQueue();
     }
 

src/com/android/settings/fuelgauge/PowerUsageFeatureProvider.java

@@ -113,4 +113,10 @@ public interface PowerUsageFeatureProvider {
      * @return A string containing the estimate and a label indicating it is a normal estimate
      */
     String getOldEstimateDebugString(String timeRemaining);
+
+    /**
+     * Returns the string to show in the advanced usage battery page when enhanced estimates are
+     * enabled. This string notifies users that the estimate is using enhanced prediction.
+     */
+    String getAdvancedUsageScreenInfoString();
 }

src/com/android/settings/fuelgauge/PowerUsageFeatureProviderImpl.java

@@ -132,4 +132,9 @@ public class PowerUsageFeatureProviderImpl implements PowerUsageFeatureProvider
     public String getOldEstimateDebugString(String timeRemaining) {
         return null;
     }
+
+    @Override
+    public String getAdvancedUsageScreenInfoString() {
+        return null;
+    }
 }