[Chromecast] Don't run stop if we didn't start.

When an app starts in background mode and then stops without being
displayed, the service-based path crashed due to calling unbindService
without calling bindService. This change prevents stop logic from being
called if start was never called.

BUG=internal 63015237
TEST=cast_shell_junit_tests

Change-Id: I8a89580927972b13d6b0842972805853b8c5bbb7
Reviewed-on: https://chromium-review.googlesource.com/576196Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Thoren Paulson <thoren@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487641}

chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastWebContentsComponent.java

@@ -137,6 +137,7 @@ public class CastWebContentsComponent {
     private OnKeyDownHandler mKeyDownHandler;
     private Receiver mReceiver;
     private String mInstanceId;
+    private boolean mStarted = false;
 
     public CastWebContentsComponent(String instanceId,
             OnComponentClosedHandler onComponentClosedHandler, OnKeyDownHandler onKeyDownHandler) {
@@ -164,13 +165,17 @@ public class CastWebContentsComponent {
         LocalBroadcastManager.getInstance(context).registerReceiver(mReceiver, filter);
 
         mDelegate.start(context, webContents);
+
+        mStarted = true;
     }
 
     public void stop(Context context) {
         if (DEBUG) Log.d(TAG, "stop");
-
+        if (mStarted) {
             LocalBroadcastManager.getInstance(context).unregisterReceiver(mReceiver);
             mDelegate.stop(context);
+            mStarted = false;
+        }
     }
 
     public static void onComponentClosed(Context context, String instanceId) {

chromecast/browser/android/junit/src/org/chromium/chromecast/shell/CastWebContentsComponentTest.java

@@ -6,6 +6,7 @@ package org.chromium.chromecast.shell;
 
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.eq;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 
 import android.app.Activity;
@@ -141,4 +142,13 @@ public class CastWebContentsComponentTest {
 
         verify(callback).onKeyDown(42);
     }
+
+    @Test
+    public void testStopDoesNotUnbindServiceIfStartWasNotCalled() {
+        CastWebContentsComponent component = new CastWebContentsComponent(INSTANCE_ID, null, null);
+
+        component.stop(mActivity);
+
+        verify(mActivity, never()).unbindService(any(ServiceConnection.class));
+    }
 }
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