Disable default CameraX initializer.

CameraX was initializing Camera2 API stuff on API < 21, causing
crashes at boot. To handle this, we disable the default
ContentProvider initializer and initialize things ourselves for
appropriate API levels.

AndroidManifest.xml

@@ -616,6 +616,11 @@
               android:authorities="org.thoughtcrime.securesms.database.stickerpack"
               android:exported="false" />
 
+    <provider android:name="androidx.camera.camera2.impl.Camera2Initializer"
+              android:authorities="${applicationId}.camerax-init"
+              android:exported="false"
+              android:enabled="false" />
+
     <receiver android:name=".service.BootReceiver">
         <intent-filter>
             <action android:name="android.intent.action.BOOT_COMPLETED"/>

src/org/thoughtcrime/securesms/ApplicationContext.java

@@ -17,6 +17,9 @@
 package org.thoughtcrime.securesms;
 
 import android.annotation.SuppressLint;
+
+import androidx.camera.camera2.Camera2AppConfig;
+import androidx.camera.core.CameraX;
 import androidx.lifecycle.DefaultLifecycleObserver;
 import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ProcessLifecycleOwner;
@@ -126,6 +129,7 @@ public class ApplicationContext extends MultiDexApplication implements Dependenc
     initializePendingMessages();
     initializeUnidentifiedDeliveryAbilityRefresh();
     initializeBlobProvider();
+    initializeCameraX();
     NotificationChannels.create(this);
     ProcessLifecycleOwner.get().getLifecycle().addObserver(this);
   }
@@ -357,6 +361,17 @@ public class ApplicationContext extends MultiDexApplication implements Dependenc
     });
   }
 
+  @SuppressLint("RestrictedApi")
+  private void initializeCameraX() {
+    if (Build.VERSION.SDK_INT >= 21) {
+      try {
+        CameraX.init(this, Camera2AppConfig.create(this));
+      } catch (Throwable t) {
+        Log.w(TAG, "Failed to initialize CameraX.");
+      }
+    }
+  }
+
   @Override
   protected void attachBaseContext(Context base) {
     super.attachBaseContext(DynamicLanguageContextWrapper.updateContext(base, TextSecurePreferences.getLanguage(base)));

src/org/thoughtcrime/securesms/mediasend/CameraFragment.java

@@ -1,14 +1,17 @@
 package org.thoughtcrime.securesms.mediasend;
 
+import android.annotation.SuppressLint;
 import android.os.Build;
 
 import androidx.annotation.NonNull;
+import androidx.camera.core.CameraX;
 import androidx.fragment.app.Fragment;
 
 public interface CameraFragment {
 
+  @SuppressLint("RestrictedApi")
   static Fragment newInstance() {
-    if (Build.VERSION.SDK_INT >= 21) {
+    if (Build.VERSION.SDK_INT >= 21 && CameraX.isInitialized()) {
       return CameraXFragment.newInstance();
     } else {
       return Camera1Fragment.newInstance();