Don't report error when encryption pattern changes on desktop Chrome

Desktop Chrome specifies the DecryptConfig with each DecoderBuffer,
so having the pattern change is handled properly. Disabling the error
check as it is only needed for Android/Chromecast.

BUG=813845,877265
TEST=manual playback of faulty video

Change-Id: I8815906388003dec66ef113148b33801034bb02f
Reviewed-on: https://chromium-review.googlesource.com/1187713Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Commit-Queue: John Rummell <jrummell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586808}

media/formats/mp4/track_run_iterator.cc

@@ -467,10 +467,11 @@ bool TrackRunIterator::Init(const MovieFragment& moof) {
           // If we don't have a per-sample IV, get the constant IV.
           bool is_encrypted = index == 0 ? track_encryption->is_encrypted
                                          : info_entry->is_encrypted;
-          // We only support setting the pattern values in the 'tenc' box for
-          // the track (not varying on per sample group basis).
-          // Thus we need to verify that the settings in the sample group match
-          // those in the 'tenc'.
+#if defined(IS_CHROMECAST)
+          // On Chromecast, we only support setting the pattern values in the
+          // 'tenc' box for the track (not varying on per sample group basis).
+          // Thus we need to verify that the settings in the sample group
+          // match those in the 'tenc'.
           if (is_encrypted && index != 0) {
             RCHECK_MEDIA_LOGGED(info_entry->crypt_byte_block ==
                                     track_encryption->default_crypt_byte_block,
@@ -485,6 +486,7 @@ bool TrackRunIterator::Init(const MovieFragment& moof) {
                                 "sample group does not match that in the tenc "
                                 "box . This is not currently supported.");
           }
+#endif  // defined(IS_CHROMECAST)
           if (is_encrypted && !iv_size) {
             const uint8_t constant_iv_size =
                 index == 0 ? track_encryption->default_constant_iv_size
@@ -495,7 +497,7 @@ bool TrackRunIterator::Init(const MovieFragment& moof) {
                            : info_entry->constant_iv;
             memcpy(entry.initialization_vector, constant_iv, constant_iv_size);
           }
-#endif
+#endif  // BUILDFLAG(ENABLE_CBCS_ENCRYPTION_SCHEME)
         }
       }
       runs_.push_back(tri);