Validate safe_browsing::dmg::UDIFBlock data before attempting to read at its offsets.

chrome/utility/safe_browsing/mac/udif.h

Index: chrome/utility/safe_browsing/mac/udif.h
diff --git a/chrome/utility/safe_browsing/mac/udif.h b/chrome/utility/safe_browsing/mac/udif.h
index 3b1a29d5280bb3d5a4d3f70d46ca62bea9e869f3..023a8729d1260e78e1d22c2c17d8feca6c52999a 100644
--- a/chrome/utility/safe_browsing/mac/udif.h
+++ b/chrome/utility/safe_browsing/mac/udif.h
@@ -76,11 +76,6 @@ class UDIFParser {
   // Parses the blkx plist trailer structure.
   bool ParseBlkx();
 
-  // Reads the data pointed to by the block |chunk|, decompressing it as
-  // necessary, into the out-buffer |decompressed_data|.
-  bool ReadBlockChunk(const UDIFBlockChunk* chunk,
-                      std::vector<uint8_t>* decompressed_data);
-
   ReadStream* const stream_;  // The stream backing the UDIF image. Weak.
   std::vector<std::string> partition_names_;  // The names of all partitions.
   ScopedVector<const UDIFBlock> blocks_;  // All blocks in the UDIF image.