[Cast,Android] Don't assume there's always a matching provider for a route

chrome/android/java/src/org/chromium/chrome/browser/media/router/ChromeMediaRouter.java

Index: chrome/android/java/src/org/chromium/chrome/browser/media/router/ChromeMediaRouter.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/media/router/ChromeMediaRouter.java b/chrome/android/java/src/org/chromium/chrome/browser/media/router/ChromeMediaRouter.java
index e8236b1667c8452009fd6d46685dfddf69c0b80b..5593a0fa3d270aab703fffa3710ae17dcf78a7ed 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/media/router/ChromeMediaRouter.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/media/router/ChromeMediaRouter.java
@@ -272,7 +272,7 @@ public class ChromeMediaRouter implements MediaRouteManager {
     @CalledByNative
     public void closeRoute(String routeId) {
         MediaRouteProvider provider = mRouteIdsToProviders.get(routeId);
-        assert provider != null;
+        if (provider == null) return;
 
         provider.closeRoute(routeId);
     }
@@ -284,7 +284,7 @@ public class ChromeMediaRouter implements MediaRouteManager {
     @CalledByNative
     public void detachRoute(String routeId) {
         MediaRouteProvider provider = mRouteIdsToProviders.get(routeId);
-        assert provider != null;
+        if (provider == null) return;
 
         provider.detachRoute(routeId);
         mRouteIdsToProviders.remove(routeId);
@@ -299,7 +299,10 @@ public class ChromeMediaRouter implements MediaRouteManager {
     @CalledByNative
     public void sendStringMessage(String routeId, String message, int callbackId) {
         MediaRouteProvider provider = mRouteIdsToProviders.get(routeId);
-        assert provider != null;
+        if (provider == null) {
+            nativeOnMessageSentResult(mNativeMediaRouterAndroid, false, callbackId);
+            return;
+        }
 
         provider.sendStringMessage(routeId, message, callbackId);
     }
@@ -313,7 +316,10 @@ public class ChromeMediaRouter implements MediaRouteManager {
     @CalledByNative
     public void sendBinaryMessage(String routeId, byte[] data, int callbackId) {
         MediaRouteProvider provider = mRouteIdsToProviders.get(routeId);
-        assert provider != null;
+        if (provider == null) {
+            nativeOnMessageSentResult(mNativeMediaRouterAndroid, false, callbackId);
+            return;
+        }
 
         provider.sendBinaryMessage(routeId, data, callbackId);
     }