Fix ANRs due to Widevine DRM plugin sniff taking too long.

Add a Widevine-specific format sniffer to avoid having to
refetch data from the remote server.

related-to-bug: 5725548

Change-Id: I622e39930f8d243111e4731557b0df17c4e2651d

proprietary/wvm/WVMExtractorImpl.cpp

@@ -80,6 +80,27 @@ WVMLoadableExtractor *GetInstance(sp<DataSource> dataSource) {
     return new WVMExtractorImpl(dataSource);
 }
 
+bool IsWidevineMedia(sp<DataSource> dataSource) {
+    char buffer[64 * 1024];
+
+    String8 uri = dataSource->getUri();
+    if (uri.getPathExtension() == ".m3u8" || uri.find(".m3u8?") != -1) {
+        // can't sniff live streams - check for .m3u8 file extension
+        return true;
+    }
+
+    ssize_t bytesRead = dataSource->readAt(0, buffer, sizeof(buffer));
+    if (bytesRead < (ssize_t)sizeof(buffer)) {
+        LOGW("IsWidevineMedia - insufficient data: %d", (int)bytesRead);
+        return false;
+    }
+
+    bool result = WV_IsWidevineMedia(buffer, sizeof(buffer));
+    return result;
+}
+
+
+
 WVMExtractorImpl::WVMExtractorImpl(sp<DataSource> dataSource)
     : mFileMetaData(new MetaData()),
       mDataSource(dataSource),