Use custom permission for unfiltered broadcast receiver in CallActivity

Signed-off-by: Álvaro Brey <alvaro.brey@nextcloud.com>

app/build.gradle

@@ -83,6 +83,10 @@ android {
         testInstrumentationRunnerArgument "TEST_SERVER_URL", "${NC_TEST_SERVER_BASEURL}"
         testInstrumentationRunnerArgument "TEST_SERVER_USERNAME", "${NC_TEST_SERVER_USERNAME}"
         testInstrumentationRunnerArgument "TEST_SERVER_PASSWORD", "${NC_TEST_SERVER_PASSWORD}"
+
+        def localBroadcastPermission = "com.nextcloud.talk.permission.PRIVATE_BROADCAST"
+        manifestPlaceholders.broadcastPermission = localBroadcastPermission
+        buildConfigField "String", "PERMISSION_LOCAL_BROADCAST", "\"${localBroadcastPermission}\""
     }
 
     buildTypes {

app/src/main/AndroidManifest.xml

@@ -79,6 +79,11 @@
     <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
     <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
 
+    <permission
+        android:name="${broadcastPermission}"
+        android:protectionLevel="signature" />
+    <uses-permission android:name="${broadcastPermission}"/>
+
     <application
         android:name=".application.NextcloudTalkApplication"
         android:allowBackup="true"

app/src/main/java/com/nextcloud/talk/activities/CallActivity.java

@@ -52,6 +52,7 @@ import android.widget.RelativeLayout;
 import android.widget.Toast;
 
 import com.bluelinelabs.logansquare.LoganSquare;
+import com.nextcloud.talk.BuildConfig;
 import com.nextcloud.talk.R;
 import com.nextcloud.talk.adapters.ParticipantDisplayItem;
 import com.nextcloud.talk.adapters.ParticipantsAdapter;
@@ -2555,7 +2556,10 @@ public class CallActivity extends CallBaseActivity {
                         }
                     }
                 };
-            registerReceiver(mReceiver, new IntentFilter(MICROPHONE_PIP_INTENT_NAME));
+            registerReceiver(mReceiver,
+                             new IntentFilter(MICROPHONE_PIP_INTENT_NAME),
+                             BuildConfig.PERMISSION_LOCAL_BROADCAST,
+                             null);
 
             updateUiForPipMode();
         } else {