manifest: Use master branch for chromium-webview

* The exact same prebuilt binaries are used across lineage releases,
  so let's eliminate the maintenance overhead of needing to pick
  updates across branches.

Change-Id: If2b11de25eee13656a1687a6d2db8e2f6da4bf80
diff --git a/default.xml b/default.xml
index be5865e..2b0466d 100644
--- a/default.xml
+++ b/default.xml
@@ -94,7 +94,7 @@
   <project path="external/cblas" name="platform/external/cblas" groups="pdk" remote="aosp" />
   <project path="external/chromium-libpac" name="platform/external/chromium-libpac" groups="pdk" remote="aosp" />
   <project path="external/chromium-trace" name="platform/external/chromium-trace" groups="pdk" remote="aosp" />
-  <project path="external/chromium-webview" name="LineageOS/android_external_chromium-webview" groups="pdk" clone-depth="1" />
+  <project path="external/chromium-webview" name="LineageOS/android_external_chromium-webview" groups="pdk" revision="master" clone-depth="1" />
   <project path="external/clang" name="platform/external/clang" groups="pdk" remote="aosp" />
   <project path="external/cmockery" name="platform/external/cmockery" groups="pdk" remote="aosp" />
   <project path="external/cn-cbor" name="platform/external/cn-cbor" groups="pdk" remote="aosp" />