Webapps: Clear AppBannerManagerAndroid::native_app_data_ prior to native app check

chrome/browser/android/banners/app_banner_manager_android.cc

Index: chrome/browser/android/banners/app_banner_manager_android.cc
diff --git a/chrome/browser/android/banners/app_banner_manager_android.cc b/chrome/browser/android/banners/app_banner_manager_android.cc
index 8ae8d3c3811869b3aaf3cf342be763678a4dab16..1849a91f3f13e164346294950f2f375b4b618106 100644
--- a/chrome/browser/android/banners/app_banner_manager_android.cc
+++ b/chrome/browser/android/banners/app_banner_manager_android.cc
@@ -158,6 +158,9 @@ bool AppBannerManagerAndroid::IsWebAppInstalled(
 }
 
 void AppBannerManagerAndroid::PerformInstallableCheck() {
+  native_app_data_.Reset();

[dominickn, 2017/02/02 06:53:38]

We should implement this correctly first up rather than in a follow-up.

Let's say we visit a page which triggers a native app banner successfully. We
will carry the native_app_data_ around incorrectly all the way up until this
method is next called.

AppBannerManager is designed such that everything is fetched once per main frame
navigation, and remains valid for the entirety of the length of time the user
spends on the page once they navigate (even if the banner is shown, the data is
still valid, and if we want to allow reshowing the banner in the future we need
to hang on to the data). That means the right place to clean up is in
AppBannerManager::DidFinishNavigation.

You should

1. Add the protected virtual AppBannerManager::ResetData() method, which has:

manifest_ = content::Manifest();
manifest_url_ = GURL();
validated_url_ = GURL();
referrer_.erase();

2. Remove the last two lines above from Stop()

3. Call ResetData() in AppBannerManager::DidFinishNavigation()

4. Override ResetData() in AppBannerManagerAndroid to add:

native_app_data_.Reset();
native_app_package_ = "";

This guarantees that once we navigate, we are back in an unfetched state until
the next fetch succeeds. We have to do a little more work but we ensure that the
banner manager is internally consistent.

+  native_app_package_ = "";
+
   // Check if the manifest prefers that we show a native app banner. If so, call
   // to Java to verify the details.
   if (manifest_.prefer_related_applications &&