Add Java module to keep the screen awake when needed.

app/src/page/file/view.js

@@ -56,6 +56,9 @@ class FilePage extends React.PureComponent {
     if (NativeModules.Mixpanel) {
       NativeModules.Mixpanel.track('Open File Page', { Uri: uri });
     }
+    if (NativeModules.UtilityModule) {
+      NativeModules.UtilityModule.keepAwakeOn();
+    }
   }
 
   componentDidUpdate() {
@@ -126,6 +129,9 @@ class FilePage extends React.PureComponent {
     if (NativeModules.ScreenOrientation) {
       NativeModules.ScreenOrientation.unlockOrientation();
     }    
+    if (NativeModules.UtilityModule) {
+      NativeModules.UtilityModule.keepAwakeOff();
+    }
   }
 
   localUriForFileInfo = (fileInfo) => {

src/main/java/io/lbry/browser/reactmodules/UtilityModule.java

@@ -0,0 +1,51 @@
+package io.lbry.browser.reactmodules;
+
+import android.app.Activity;
+import android.content.Context;
+import android.view.WindowManager;
+
+import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.bridge.ReactContextBaseJavaModule;
+import com.facebook.react.bridge.ReactMethod;
+
+public class UtilityModule extends ReactContextBaseJavaModule {
+    private Context context;
+
+    public UtilityModule(ReactApplicationContext reactContext) {
+        super(reactContext);
+        this.context = reactContext;
+    }
+
+    @Override
+    public String getName() {
+        return "UtilityModule";
+    }
+
+    @ReactMethod
+    public void keepAwakeOn() {
+      final Activity activity = getCurrentActivity();
+
+      if (activity != null) {
+        activity.runOnUiThread(new Runnable() {
+          @Override
+          public void run() {
+            activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
+          }
+        });
+      }
+    }
+
+    @ReactMethod
+    public void keepAwakeOff() {
+      final Activity activity = getCurrentActivity();
+
+      if (activity != null) {
+        activity.runOnUiThread(new Runnable() {
+          @Override
+          public void run() {
+            activity.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
+          }
+        });
+      }
+    }
+}

src/main/java/io/lbry/browser/reactpackages/LbryReactPackage.java

@@ -11,6 +11,7 @@ import io.lbry.browser.reactmodules.FirstRunModule;
 import io.lbry.browser.reactmodules.MixpanelModule;
 import io.lbry.browser.reactmodules.ScreenOrientationModule;
 import io.lbry.browser.reactmodules.VersionInfoModule;
+import io.lbry.browser.reactmodules.UtilityModule;;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -31,6 +32,7 @@ public class LbryReactPackage implements ReactPackage {
         modules.add(new FirstRunModule(reactContext));
         modules.add(new MixpanelModule(reactContext));
         modules.add(new ScreenOrientationModule(reactContext));
+        modules.add(new UtilityModule(reactContext));
         modules.add(new VersionInfoModule(reactContext));
 
         return modules;