Fixes for re-enabling more MSVC level 4 warnings: media/ edition

media/cast/rtcp/test_rtcp_packet_builder.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/cast/rtcp/test_rtcp_packet_builder.h"
 
 #include "base/logging.h"
 #include "media/cast/rtcp/rtcp_utility.h"
 
 namespace media {
@@ skipping 47 matching lines @@
   AddRtcpHeader(202, 1);
   big_endian_writer_.WriteU32(sender_ssrc);
   big_endian_writer_.WriteU8(1);  // c_name.
 
   DCHECK_LE(c_name.size(), 255u);
   big_endian_writer_.WriteU8(
       static_cast<uint8>(c_name.size()));  // c_name length in bytes.
   for (size_t i = 0; i < c_name.size(); ++i) {
     big_endian_writer_.WriteU8(c_name.c_str()[i]);
   }
-  int padding;
-  switch (c_name.size() % 4) {
-    case 0:
-      padding = 2;
-      break;
-    case 1:
-      padding = 1;
-      break;
-    case 2:
-      padding = 4;
-      break;
-    case 3:
-      padding = 3;
-      break;
-  }
+  const int padding = (6 - (c_name.size() % 4)) % 4;

[ddorwin, 2014/07/08 18:17:50]

"case 2" was 4 and is now 0.

[Peter Kasting, 2014/07/08 18:39:14]

Good catch.  Fixed.

Although I'm not sure it actually matters -- I assume this code is just here to
pad things out so the next item written will have 4-byte alignment, in which
case writing 4 bytes of padding is the same as writing no padding (except for
wasting some space?).  And the trybots seemed to pass, so it seems like
unittests don't rely on the distinction.

However, this patch isn't supposed to change behavior, so fixing it is the right
thing anyway.

   for (int j = 0; j < padding; ++j) {
     big_endian_writer_.WriteU8(0);
   }
 }
 
 void TestRtcpPacketBuilder::AddXrHeader(uint32 sender_ssrc) {
   AddRtcpHeader(207, 0);
   big_endian_writer_.WriteU32(sender_ssrc);
 }
 
@@ skipping 181 matching lines @@
   big_endian_writer_.WriteU8(0x80 | (format_or_count & 0x1F));
   big_endian_writer_.WriteU8(payload);
   ptr_of_length_ = big_endian_writer_.ptr();
 
   // Initialize length to "clearly illegal".
   big_endian_writer_.WriteU16(0xDEAD);
 }
 
 }  // namespace cast
 }  // namespace media