Update libyuv URL in vp9 extension instructions

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=109559103

extensions/vp9/README.md

@@ -35,7 +35,7 @@ NDK_PATH="<path to Android NDK>"
 ```
 ```
 cd "${VP9_EXT_PATH}/jni" && \
 cd "${VP9_EXT_PATH}/jni" && \
 git clone https://chromium.googlesource.com/webm/libvpx libvpx && \
 git clone https://chromium.googlesource.com/webm/libvpx libvpx && \
-git clone https://git.chromium.org/external/libyuv.git libyuv
+git clone https://chromium.googlesource.com/external/libyuv libyuv
 ```
 ```
 
 
 * Run a script that generates necessary configuration files for libvpx
 * Run a script that generates necessary configuration files for libvpx