Default emergency gesture setting On.

And a few drive-by fixes:
* Move all emergency gesture fragments and controllers to emergency
  package for better code colocation.
* Remove the placeholder video preference from emergency_gesture_settings.xml

Bug: 178009196
Test: reran robotests
Change-Id: Ifcb591e7ab8e5e5494c480cbbe9410c08c296f8e

src/com/android/settings/emergency/EmergencyGestureEntrypointPreferenceController.java

@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.emergency;
+
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
+import android.text.TextUtils;
+import android.util.Log;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.Preference;
+
+import com.android.settings.R;
+import com.android.settings.core.BasePreferenceController;
+
+/**
+ * Preference controller for emergency gesture setting's entyrpoint preference
+ */
+public class EmergencyGestureEntrypointPreferenceController extends BasePreferenceController {
+    private static final String TAG = "EmergencyGestureEntry";
+
+    @VisibleForTesting
+    static final String ACTION_EMERGENCY_GESTURE_SETTINGS =
+            "com.android.settings.action.emergency_gesture_settings";
+    @VisibleForTesting
+    Intent mIntent;
+
+    private boolean mUseCustomIntent;
+
+    public EmergencyGestureEntrypointPreferenceController(Context context, String key) {
+        super(context, key);
+        final String emergencyGestureSettingsPackageName = context.getResources().getString(
+                R.string.emergency_gesture_settings_package);
+        if (!TextUtils.isEmpty(emergencyGestureSettingsPackageName)) {
+            mUseCustomIntent = true;
+            // Use custom intent if it's configured and system can resolve it.
+            final Intent intent = new Intent(ACTION_EMERGENCY_GESTURE_SETTINGS)
+                    .setPackage(emergencyGestureSettingsPackageName);
+            if (canResolveIntent(intent)) {
+                mIntent = intent;
+            }
+        }
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+        final boolean canHandleClicks = !mUseCustomIntent || mIntent != null;
+        if (preference != null) {
+            preference.setEnabled(canHandleClicks);
+        }
+    }
+
+    @Override
+    public boolean handlePreferenceTreeClick(Preference preference) {
+        if (TextUtils.equals(getPreferenceKey(), preference.getKey()) && mIntent != null) {
+            mIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
+            mContext.startActivity(mIntent);
+            return true;
+        }
+        return super.handlePreferenceTreeClick(preference);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        final boolean isConfigEnabled = mContext.getResources()
+                .getBoolean(R.bool.config_show_emergency_gesture_settings);
+
+        if (!isConfigEnabled) {
+            return UNSUPPORTED_ON_DEVICE;
+        }
+        return AVAILABLE;
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        if (mUseCustomIntent) {
+            final String packageName = mContext.getResources().getString(
+                    R.string.emergency_gesture_settings_package);
+            try {
+                final PackageManager pm = mContext.getPackageManager();
+                final ApplicationInfo appInfo = pm.getApplicationInfo(
+                        packageName, PackageManager.MATCH_DISABLED_COMPONENTS
+                                | PackageManager.MATCH_DISABLED_UNTIL_USED_COMPONENTS);
+                return mContext.getString(R.string.emergency_gesture_entrypoint_summary,
+                        appInfo.loadLabel(pm));
+            } catch (Exception e) {
+                Log.d(TAG, "Failed to get custom summary, falling back.");
+                return super.getSummary();
+            }
+        }
+
+        return super.getSummary();
+    }
+
+    /**
+     * Whether or not gesture page content should be suppressed from search.
+     */
+    public boolean shouldSuppressFromSearch() {
+        return mUseCustomIntent;
+    }
+
+    private boolean canResolveIntent(Intent intent) {
+        final ResolveInfo resolveActivity = mContext.getPackageManager()
+                .resolveActivity(intent, 0);
+        return resolveActivity != null;
+    }
+}