Handle empty RawCC files.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=143667717

library/src/main/java/com/google/android/exoplayer2/extractor/rawcc/RawCcExtractor.java

@@ -83,8 +83,11 @@ public final class RawCcExtractor implements Extractor {
     while (true) {
       switch (parserState) {
         case STATE_READING_HEADER:
-          parseHeader(input);
-          parserState = STATE_READING_TIMESTAMP_AND_COUNT;
+          if (parseHeader(input)) {
+            parserState = STATE_READING_TIMESTAMP_AND_COUNT;
+          } else {
+            return RESULT_END_OF_INPUT;
+          }
           break;
         case STATE_READING_TIMESTAMP_AND_COUNT:
           if (parseTimestampAndSampleCount(input)) {
@@ -114,14 +117,18 @@ public final class RawCcExtractor implements Extractor {
     // Do nothing
   }
 
-  private void parseHeader(ExtractorInput input) throws IOException, InterruptedException {
+  private boolean parseHeader(ExtractorInput input) throws IOException, InterruptedException {
     dataScratch.reset();
-    input.readFully(dataScratch.data, 0, HEADER_SIZE);
-    if (dataScratch.readInt() != HEADER_ID) {
-      throw new IOException("Input not RawCC");
+    if (input.readFully(dataScratch.data, 0, HEADER_SIZE, true)) {
+      if (dataScratch.readInt() != HEADER_ID) {
+        throw new IOException("Input not RawCC");
+      }
+      version = dataScratch.readUnsignedByte();
+      // no versions use the flag fields yet
+      return true;
+    } else {
+      return false;
     }
-    version = dataScratch.readUnsignedByte();
-    // no versions use the flag fields yet
   }
 
   private boolean parseTimestampAndSampleCount(ExtractorInput input) throws IOException,