Implemented conversation search.

You can now search for messages within a specific conversation.

src/org/thoughtcrime/securesms/components/ConversationSearchBottomBar.java

@@ -0,0 +1,88 @@
+package org.thoughtcrime.securesms.components;
+
+import android.content.Context;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.constraint.ConstraintLayout;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.TextView;
+
+import org.thoughtcrime.securesms.R;
+
+/**
+ * Bottom navigation bar shown in the {@link org.thoughtcrime.securesms.conversation.ConversationActivity}
+ * when the user is searching within a conversation. Shows details about the results and allows the
+ * user to move between them.
+ */
+public class ConversationSearchBottomBar extends ConstraintLayout {
+
+  private View     searchDown;
+  private View     searchUp;
+  private TextView searchPositionText;
+  private View     progressWheel;
+
+  private EventListener eventListener;
+
+
+  public ConversationSearchBottomBar(Context context) {
+    super(context);
+  }
+
+  public ConversationSearchBottomBar(Context context, AttributeSet attrs) {
+    super(context, attrs);
+  }
+
+  @Override
+  protected void onFinishInflate() {
+    super.onFinishInflate();
+
+    this.searchUp           = findViewById(R.id.conversation_search_up);
+    this.searchDown         = findViewById(R.id.conversation_search_down);
+    this.searchPositionText = findViewById(R.id.conversation_search_position);
+    this.progressWheel      = findViewById(R.id.conversation_search_progress_wheel);
+  }
+
+  public void setData(int position, int count) {
+    progressWheel.setVisibility(GONE);
+
+    searchUp.setOnClickListener(v -> {
+      if (eventListener != null) {
+        eventListener.onSearchMoveUpPressed();
+      }
+    });
+
+    searchDown.setOnClickListener(v -> {
+      if (eventListener != null) {
+        eventListener.onSearchMoveDownPressed();
+      }
+    });
+
+    if (count > 0) {
+      searchPositionText.setText(getResources().getString(R.string.ConversationActivity_search_position, position + 1, count));
+    } else {
+      searchPositionText.setText(R.string.ConversationActivity_no_results);
+    }
+
+    setViewEnabled(searchUp, position < (count - 1));
+    setViewEnabled(searchDown, position > 0);
+  }
+
+  public void showLoading() {
+    progressWheel.setVisibility(VISIBLE);
+  }
+
+  private void setViewEnabled(@NonNull View view, boolean enabled) {
+    view.setEnabled(enabled);
+    view.setAlpha(enabled ? 1f : 0.25f);
+  }
+
+  public void setEventListener(@Nullable EventListener eventListener) {
+    this.eventListener = eventListener;
+  }
+
+  public interface EventListener {
+    void onSearchMoveUpPressed();
+    void onSearchMoveDownPressed();
+  }
+}