Fix a bug that H264BitReader::ReadBits cannot read more than 16 bits.

content/common/gpu/media/h264_bit_reader.cc

Index: content/common/gpu/media/h264_bit_reader.cc
diff --git a/content/common/gpu/media/h264_bit_reader.cc b/content/common/gpu/media/h264_bit_reader.cc
index f2d2f356c49bab1ddde9e866f1fbf9c14ef7e3ca..64e12bee203ecfdcd34322faabbde9362d31c5f2 100644
--- a/content/common/gpu/media/h264_bit_reader.cc
+++ b/content/common/gpu/media/h264_bit_reader.cc
@@ -66,7 +66,7 @@ bool H264BitReader::ReadBits(int num_bits, int *out) {
 
   while (num_remaining_bits_in_curr_byte_ < bits_left) {
     // Take all that's left in current byte, shift to make space for the rest.
-    *out = (curr_byte_ << (bits_left - num_remaining_bits_in_curr_byte_));
+    *out |= (curr_byte_ << (bits_left - num_remaining_bits_in_curr_byte_));
     bits_left -= num_remaining_bits_in_curr_byte_;
 
     if (!UpdateCurrByte())