[Snap] Fix beta/dev package builds

Braces are needed around LOGO otherwise bash will look for variables
called LOGO_beta and LOGO_dev, which is not the intention.

BUG=1055026,1090915
R=dpranke

Change-Id: I3462151be1f632f3c2be145d8c1123c9c3886175
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2236228
Auto-Submit: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776195}

chrome/installer/linux/snap/build.sh

@@ -56,9 +56,9 @@ process_template "${SCRIPTDIR}/snapcraft.yaml.in" "${TMPFILEDIR}/snapcraft.yaml"
 if [ "$SNAPNAME" = "google-chrome" ]; then
   LOGO="product_logo_256"
   if [ "$CHANNEL" = "beta" ]; then
-    sed -i -e "s:$LOGO.png:$LOGO_beta.png:" "${TMPFILEDIR}/snapcraft.yaml"
+    sed -i -e "s:$LOGO.png:${LOGO}_beta.png:" "${TMPFILEDIR}/snapcraft.yaml"
   elif [ "$CHANNEL" = "unstable" ]; then
-    sed -i -e "s:$LOGO.png:$LOGO_dev.png:" "${TMPFILEDIR}/snapcraft.yaml"
+    sed -i -e "s:$LOGO.png:${LOGO}_dev.png:" "${TMPFILEDIR}/snapcraft.yaml"
   fi
 fi