Android: Fix ClassCastException on launch in DexFixer

Changed versionCode from int to long, which apparently does not
auto-convert.

Bug: 1163674
Change-Id: Ia213c65d437adf6f98caee0ba44c084534360b2c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611975
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840915}

chrome/browser/preferences/android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceKeys.java

@@ -469,7 +469,7 @@ public final class ChromePreferenceKeys {
      * details.
      */
     public static final String ISOLATED_SPLITS_DEX_COMPILE_VERSION =
-            "Chrome.IsolatedSplits.DexCompileVersion";
+            "Chrome.IsolatedSplits.VersionCode";
 
     /**
      * When the user is shown a badge that the current Android OS version is unsupported, and they