Fix user agent override when the page has iframes. (#910)

GeckoView is calling onLoadRequest multiple times for a single page with different URLs. The additional calls were breaking the UA override code. This work around prevents the UA override code from being called more than once and only for the first onLoadRequest.

app/src/common/shared/org/mozilla/vrbrowser/browser/SessionStore.java

@@ -945,10 +945,17 @@ public void onCanGoForward(GeckoSession aSession, boolean aCanGoForward) {
         }
     }
 
+    public boolean mFirstOnLoadRequest = true;
+
     @Override
     public @Nullable GeckoResult<AllowOrDeny> onLoadRequest(@NonNull GeckoSession aSession, @NonNull LoadRequest aRequest) {
         final GeckoResult<AllowOrDeny> result = new GeckoResult<>();
-        aSession.getSettings().setString(GeckoSessionSettings.USER_AGENT_OVERRIDE, mUserAgentOverride.lookupOverride(aRequest.uri));
+        Log.d(LOGTAG, "onLoadRequest: " + aRequest.uri);
+        if (mFirstOnLoadRequest && (aSession == mCurrentSession)) {
+            Log.d(LOGTAG, "Testing for UA override");
+            aSession.getSettings().setString(GeckoSessionSettings.USER_AGENT_OVERRIDE, mUserAgentOverride.lookupOverride(aRequest.uri));
+            mFirstOnLoadRequest = false;
+        }
         if (PRIVATE_BROWSING_URI.equalsIgnoreCase(aRequest.uri)) {
             switchPrivateMode();
             result.complete(AllowOrDeny.ALLOW);
@@ -1076,6 +1083,7 @@ public void onPageStop(GeckoSession aSession, boolean b) {
         }
 
         if (mCurrentSession == aSession) {
+            mFirstOnLoadRequest = true;
             for (GeckoSession.ProgressDelegate listener : mProgressListeners) {
                 listener.onPageStop(aSession, b);
             }