Add UMA stats for audio/video containers.

media/base/bit_reader.cc

Index: media/base/bit_reader.cc
diff --git a/media/base/bit_reader.cc b/media/base/bit_reader.cc
index ed3dc6050f1f11383db82d6784c37ff82e9d124b..55b9b7e412c01991b9e273d11500703f174318e5 100644
--- a/media/base/bit_reader.cc
+++ b/media/base/bit_reader.cc
@@ -15,6 +15,29 @@ BitReader::BitReader(const uint8* data, off_t size)
 
 BitReader::~BitReader() {}
 
+bool BitReader::SkipBits(int num_bits) {
+  DCHECK_GE(num_bits, 0);
+
+  // Skip any bits in the current byte waiting to be processed, then
+  // process full bytes until less than 8 bits remaining.
+  while (num_bits > 0 && num_bits > num_remaining_bits_in_curr_byte_) {
+    num_bits -= num_remaining_bits_in_curr_byte_;
+    num_remaining_bits_in_curr_byte_ = 0;
+    UpdateCurrByte();

[xhwang, 2013/05/22 22:18:32]

nit: can we skip multiple bytes in one operation instead of skip one byte for
multiple times?

[jrummell, 2013/05/22 23:59:46]

I added a DLOG message to print a warning if large skips are encountered, so
that the code could be optimized.

+
+    // If there is no more data remaining, only return true if we
+    // skipped all that were requested.
+    if (num_remaining_bits_in_curr_byte_ == 0)
+      return (num_bits == 0);
+  }
+
+  // Less than 8 bits remaining to skip. Use ReadBitsInternal to verify
+  // that the remaining bits we need exist, and adjust them as necessary
+  // for subsequent operations.
+  uint64 not_needed;
+  return ReadBitsInternal(num_bits, &not_needed);
+}
+
 int BitReader::bits_available() const {
   return 8 * bytes_left_ + num_remaining_bits_in_curr_byte_;
 }