FileWrapper[Impl] modifications and actually remove the "Impl" class.

webrtc/modules/media_file/media_file_utility.cc

Index: webrtc/modules/media_file/media_file_utility.cc
diff --git a/webrtc/modules/media_file/media_file_utility.cc b/webrtc/modules/media_file/media_file_utility.cc
index 8a815cc25d6c1f0ab4f480a95f0d265dedeeb43d..8e7c8f6a028383f890b57d6bbc65c6447088253e 100644
--- a/webrtc/modules/media_file/media_file_utility.cc
+++ b/webrtc/modules/media_file/media_file_utility.cc
@@ -1456,12 +1456,11 @@ int32_t ModuleFileUtility::FileDurationMs(const char* fileName,
                      "failed to create InStream object!");
         return -1;
     }
-    if(inStreamObj->OpenFile(fileName, true) == -1)
-    {
-        delete inStreamObj;
-        WEBRTC_TRACE(kTraceError, kTraceFile, _id,
-                     "failed to open file %s!", fileName);
-        return -1;
+    if (!inStreamObj->OpenFile(fileName, true)) {
+      delete inStreamObj;
+      WEBRTC_TRACE(kTraceError, kTraceFile, _id, "failed to open file %s!",
+                   fileName);
+      return -1;
     }
 
     switch (fileFormat)