title: Google Maps Flutter: I am getting black screen before loading maps
body: <p>I am getting black screen before loading maps, I tried creating a map widget on build() method and store it in a variable to use it whenever i open bottom sheet but i am still facing the same issue. Please have a look at the screenshot below:</p>
  
  <p><a href="https://user-images.githubusercontent.com/7915601/64229575-9d27e600-cf03-11e9-8619-9a7d1892d58d.gif" rel="noreferrer">https://user-images.githubusercontent.com/7915601/64229575-9d27e600-cf03-11e9-8619-9a7d1892d58d.gif</a></p>
  
  <p><strong>Code</strong></p>
  
  <pre><code>  Widget _buildMap() {
      return Expanded(
        flex: 1,
        child: MapWidget(
          initialLocation: _center,
          zoomLevel: 11.0,
          locations: _jobStore.jobLocations,
          onMarkerTap: (id) {
            print('job id: $id');
            _jobStore.onItemClick(jobId: int.tryParse(id) ?? 0);
          },
        ),
      );
    }
  </code></pre>
  
  <p><strong>Flutter doctor</strong></p>
  
  <pre><code>macs-mbp:cubivue_app mac$ flutter doctor -v
  [✓] Flutter (Channel stable, v1.7.8+hotfix.4, on Mac OS X 10.14.6 18G87, locale en-PK)
      • Flutter version 1.7.8+hotfix.4 at /Users/mac/Documents/flutter
      • Framework revision 20e59316b8 (7 weeks ago), 2019-07-18 20:04:33 -0700
      • Engine revision fee001c93f
      • Dart version 2.4.0
  
  
  [✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
      • Android SDK at /Users/mac/Library/Android/sdk
      • Android NDK location not configured (optional; useful for native profiling support)
      • Platform android-29, build-tools 29.0.2
      • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
      • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
      • All Android licenses accepted.
  
  [✓] Xcode - develop for iOS and macOS (Xcode 10.3)
      • Xcode at /Applications/Xcode.app/Contents/Developer
      • Xcode 10.3, Build version 10G8
      • CocoaPods version 1.7.5
  
  [✓] iOS tools - develop for iOS devices
      • ios-deploy 1.9.4
  
  [✓] Android Studio (version 3.5)
      • Android Studio at /Applications/Android Studio.app/Contents
      • Flutter plugin version 38.2.3
      • Dart plugin version 191.8423
      • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
  
  [✓] Connected device (1 available)
      • BV5500Pro • E535B1ZM960411E2 • android-arm • Android 9 (API 28)
  
  • No issues found!
  
  </code></pre>