[GCM] Investigatory CHECKs for crash in parsing stream

google_apis/gcm/base/socket_stream.cc

Index: google_apis/gcm/base/socket_stream.cc
diff --git a/google_apis/gcm/base/socket_stream.cc b/google_apis/gcm/base/socket_stream.cc
index 14889e1f1180d3e0b45ba3a1db6d517c7f012697..edf723cdabdaf4931c4402f3b45b741925385cf6 100644
--- a/google_apis/gcm/base/socket_stream.cc
+++ b/google_apis/gcm/base/socket_stream.cc
@@ -56,8 +56,9 @@ bool SocketInputStream::Next(const void** data, int* size) {
 
 void SocketInputStream::BackUp(int count) {
   DCHECK(GetState() == READY || GetState() == EMPTY);
-  DCHECK_GT(count, 0);
-  DCHECK_LE(count, next_pos_);
+  // TODO(zea): investigating crbug.com/409985
+  CHECK_GT(count, 0);
+  CHECK_LE(count, next_pos_);
 
   next_pos_ -= count;
   DVLOG(1) << "Backing up " << count << " bytes in input buffer. "
@@ -76,7 +77,7 @@ int64 SocketInputStream::ByteCount() const {
   return next_pos_;
 }
 
-size_t SocketInputStream::UnreadByteCount() const {
+int SocketInputStream::UnreadByteCount() const {
   DCHECK_NE(GetState(), CLOSED);
   DCHECK_NE(GetState(), READING);
   return read_buffer_->BytesConsumed() - next_pos_;
@@ -137,6 +138,8 @@ void SocketInputStream::RebuildBuffer() {
     DVLOG(1) << "Have " << unread_data_size << " unread bytes remaining.";
   }
   read_buffer_->DidConsume(unread_data_size);
+  // TODO(zea): investigating crbug.com/409985
+  CHECK_GE(UnreadByteCount(), 0);
 }
 
 net::Error SocketInputStream::last_error() const {
@@ -179,6 +182,8 @@ void SocketInputStream::RefreshCompletionCallback(
   DCHECK_GT(result, 0);
   last_error_ = net::OK;
   read_buffer_->DidConsume(result);
+  // TODO(zea): investigating crbug.com/409985
+  CHECK_GT(UnreadByteCount(), 0);
 
   DVLOG(1) << "Refresh complete with " << result << " new bytes. "
            << "Current position " << next_pos_