Ignore cache span rename error

This happens rarely and SimpleCache can continue fine.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=209759996

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CachedContent.java

@@ -185,16 +185,13 @@ import java.util.TreeSet;
    * @throws CacheException If renaming of the underlying span file failed.
    */
   public SimpleCacheSpan touch(SimpleCacheSpan cacheSpan) throws CacheException {
-    // Remove the old span from the in-memory representation.
-    Assertions.checkState(cachedSpans.remove(cacheSpan));
-    // Obtain a new span with updated last access timestamp.
     SimpleCacheSpan newCacheSpan = cacheSpan.copyWithUpdatedLastAccessTime(id);
-    // Rename the cache file
     if (!cacheSpan.file.renameTo(newCacheSpan.file)) {
       throw new CacheException("Renaming of " + cacheSpan.file + " to " + newCacheSpan.file
           + " failed.");
     }
-    // Add the updated span back into the in-memory representation.
+    // Replace the in-memory representation of the span.
+    Assertions.checkState(cachedSpans.remove(cacheSpan));
     cachedSpans.add(newCacheSpan);
     return newCacheSpan;
   }

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/SimpleCache.java

@@ -232,10 +232,16 @@ public final class SimpleCache implements Cache {
 
     // Read case.
     if (cacheSpan.isCached) {
-      // Obtain a new span with updated last access timestamp.
-      SimpleCacheSpan newCacheSpan = index.get(key).touch(cacheSpan);
-      notifySpanTouched(cacheSpan, newCacheSpan);
-      return newCacheSpan;
+      try {
+        // Obtain a new span with updated last access timestamp.
+        SimpleCacheSpan newCacheSpan = index.get(key).touch(cacheSpan);
+        notifySpanTouched(cacheSpan, newCacheSpan);
+        return newCacheSpan;
+      } catch (CacheException e) {
+        // Ignore. In worst case the cache span is evicted early.
+        // This happens very rarely [Internal: b/38351639]
+        return cacheSpan;
+      }
     }
 
     CachedContent cachedContent = index.getOrAdd(key);