Check if info for uri is available

before retrieving it.

Bug: 17683986
Change-Id: I7a44cd06faf11c22be2ed5ace8ab6e2a5513b66c
diff --git a/media/libstagefright/httplive/LiveSession.cpp b/media/libstagefright/httplive/LiveSession.cpp
index 7a9a1a3..fba6b09 100644
--- a/media/libstagefright/httplive/LiveSession.cpp
+++ b/media/libstagefright/httplive/LiveSession.cpp
@@ -494,6 +494,10 @@
                     AString uri;
                     CHECK(msg->findString("uri", &uri));
 
+                    if (mFetcherInfos.indexOfKey(uri) < 0) {
+                        ALOGE("couldn't find uri");
+                        break;
+                    }
                     FetcherInfo *info = &mFetcherInfos.editValueFor(uri);
                     info->mIsPrepared = true;