Create placeholder ContentProviders for database observations.

Required for the API 26 migration.

See https://developer.android.com/about/versions/oreo/android-8.0-changes#ccn

AndroidManifest.xml

@@ -557,6 +557,18 @@
 
     </provider>
 
+    <provider android:name=".database.DatabaseContentProviders$Conversation"
+              android:authorities="org.thoughtcrime.securesms.database.conversation"
+              android:exported="false" />
+
+    <provider android:name=".database.DatabaseContentProviders$ConversationList"
+              android:authorities="org.thoughtcrime.securesms.database.conversationlist"
+              android:exported="false" />
+
+    <provider android:name=".database.DatabaseContentProviders$Attachment"
+              android:authorities="org.thoughtcrime.securesms.database.attachment"
+              android:exported="false" />
+
     <receiver android:name=".service.BootReceiver">
         <intent-filter>
             <action android:name="android.intent.action.BOOT_COMPLETED"/>

src/org/thoughtcrime/securesms/database/Database.java

@@ -28,10 +28,7 @@ import java.util.Set;
 
 public abstract class Database {
 
-  protected static final String ID_WHERE              = "_id = ?";
-  private   static final String CONVERSATION_URI      = "content://textsecure/thread/";
-  private   static final String CONVERSATION_LIST_URI = "content://textsecure/conversation-list";
-  private   static final String ATTACHMENT_URI        = "content://textsecure/attachment/";
+  protected static final String ID_WHERE = "_id = ?";
 
   protected       SQLCipherOpenHelper databaseHelper;
   protected final Context             context;
@@ -47,29 +44,29 @@ public abstract class Database {
   }
 
   protected void notifyConversationListeners(long threadId) {
-    context.getContentResolver().notifyChange(Uri.parse(CONVERSATION_URI + threadId), null);
+    context.getContentResolver().notifyChange(DatabaseContentProviders.Conversation.getUriForThread(threadId), null);
   }
 
   protected void notifyConversationListListeners() {
-    context.getContentResolver().notifyChange(Uri.parse(CONVERSATION_LIST_URI), null);
+    context.getContentResolver().notifyChange(DatabaseContentProviders.ConversationList.CONTENT_URI, null);
   }
 
   protected void setNotifyConverationListeners(Cursor cursor, long threadId) {
-    cursor.setNotificationUri(context.getContentResolver(), Uri.parse(CONVERSATION_URI + threadId));
+    cursor.setNotificationUri(context.getContentResolver(), DatabaseContentProviders.Conversation.getUriForThread(threadId));
   }
 
   protected void setNotifyConverationListListeners(Cursor cursor) {
-    cursor.setNotificationUri(context.getContentResolver(), Uri.parse(CONVERSATION_LIST_URI));
+    cursor.setNotificationUri(context.getContentResolver(), DatabaseContentProviders.ConversationList.CONTENT_URI);
   }
 
   protected void registerAttachmentListeners(@NonNull ContentObserver observer) {
-    context.getContentResolver().registerContentObserver(Uri.parse(ATTACHMENT_URI),
+    context.getContentResolver().registerContentObserver(DatabaseContentProviders.Attachment.CONTENT_URI,
                                                          true,
                                                          observer);
   }
 
   protected void notifyAttachmentListeners() {
-    context.getContentResolver().notifyChange(Uri.parse(ATTACHMENT_URI), null);
+    context.getContentResolver().notifyChange(DatabaseContentProviders.Attachment.CONTENT_URI, null);
   }
 
   public void reset(SQLCipherOpenHelper databaseHelper) {

src/org/thoughtcrime/securesms/database/DatabaseContentProviders.java

@@ -0,0 +1,67 @@
+package org.thoughtcrime.securesms.database;
+
+import android.content.ContentProvider;
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.net.Uri;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+/**
+ * Starting in API 26, a {@link ContentProvider} needs to be defined for each authority you wish to
+ * observe changes on. These classes essentially do nothing except exist so Android doesn't complain.
+ */
+public class DatabaseContentProviders {
+
+  public static class ConversationList extends NoopContentProvider {
+    public static final Uri CONTENT_URI = Uri.parse("content://org.thoughtcrime.securesms.database.conversationlist");
+  }
+
+  public static class Conversation extends NoopContentProvider {
+    private static final String CONTENT_URI_STRING = "content://org.thoughtcrime.securesms.database.conversation/";
+
+    public static Uri getUriForThread(long threadId) {
+      return Uri.parse(CONTENT_URI_STRING + threadId);
+    }
+  }
+
+  public static class Attachment extends NoopContentProvider {
+    public static final Uri CONTENT_URI = Uri.parse("content://org.thoughtcrime.securesms.database.attachment");
+  }
+
+  private static abstract class NoopContentProvider extends ContentProvider {
+
+    @Override
+    public boolean onCreate() {
+      return false;
+    }
+
+    @Nullable
+    @Override
+    public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection, @Nullable String[] selectionArgs, @Nullable String sortOrder) {
+      return null;
+    }
+
+    @Nullable
+    @Override
+    public String getType(@NonNull Uri uri) {
+      return null;
+    }
+
+    @Nullable
+    @Override
+    public Uri insert(@NonNull Uri uri, @Nullable ContentValues values) {
+      return null;
+    }
+
+    @Override
+    public int delete(@NonNull Uri uri, @Nullable String selection, @Nullable String[] selectionArgs) {
+      return 0;
+    }
+
+    @Override
+    public int update(@NonNull Uri uri, @Nullable ContentValues values, @Nullable String selection, @Nullable String[] selectionArgs) {
+      return 0;
+    }
+  }
+}