Fix invalid reads detected by Valgrind when the frame size changes.

third_party/ffmpeg/README.chromium

Index: third_party/ffmpeg/README.chromium
===================================================================
--- third_party/ffmpeg/README.chromium	(revision 109270)
+++ third_party/ffmpeg/README.chromium	(working copy)
@@ -67,6 +67,7 @@
        patch -p1 --no-backup-if-mismatch < ../patches/to_upstream/47_vp3_fix_infloop_and_memleak.patch
        patch -p1 --no-backup-if-mismatch < ../patches/to_upstream/48_vorbis_residue_buffer.patch
        patch -p1 --no-backup-if-mismatch < ../patches/to_upstream/49_vorbis_buffer_defense.patch
+       patch -p1 --no-backup-if-mismatch < ../patches/to_upstream/50_vp8_fix_frame_size_changes.patch
        cd ..
 
 
@@ -333,6 +334,14 @@
        diff -wurp -N orig ffmpeg
        diff -wurp -N orig ffmpeg >patches/to_upstream/49_vorbis_buffer_defense.patch
 
+       rm -rf orig
+       cp -R ffmpeg orig
+       cd ffmpeg
+       patch -p1 --no-backup-if-mismatch < ../patches/to_upstream/49_vorbis_buffer_defense.patch
+       cd ..
+       diff -wurp -N orig ffmpeg
+       diff -wurp -N orig ffmpeg >patches/to_upstream/50_vp8_fix_frame_size_changes.patch
+
 Testing
   Updates should be tested against
   a) http://wiki.xiph.org/TheoraTestsuite