Fixes redirects to external apps when navigating from PWA.

chrome/android/javatests/src/org/chromium/chrome/browser/webapps/TopActivityListener.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/webapps/TopActivityListener.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/TopActivityListener.java b/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/TopActivityListener.java
index e746f7ef9e885cf561e4b790229c33aee216002c..479ee024c4132d5cb0322d54d1106872e6c833b9 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/TopActivityListener.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/TopActivityListener.java
@@ -16,6 +16,8 @@ import org.chromium.base.ApplicationStatus.ActivityStateListener;
 import org.chromium.content.browser.test.util.Criteria;
 import org.chromium.content.browser.test.util.CriteriaHelper;
 
+import java.util.concurrent.TimeUnit;
+
 import javax.annotation.Nullable;
 
 /**
@@ -27,10 +29,14 @@ public class TopActivityListener implements TestRule {
         public void onActivityStateChange(Activity activity, int newState) {
             if (newState == ActivityState.RESUMED) {
                 mMostRecentActivity = activity;
+            } else if (activity == mMostRecentActivity && newState == ActivityState.PAUSED) {
+                mMostRecentActivity = null;
+                mTimeWhenSetToNullMillis = System.currentTimeMillis();
             }
         }
     };
 
+    private long mTimeWhenSetToNullMillis;
     private Activity mMostRecentActivity;
 
     @Override
@@ -61,4 +67,15 @@ public class TopActivityListener implements TestRule {
         });
         return (T) mMostRecentActivity;
     }
+
+    public void waitForExternalApp() {
+        CriteriaHelper.pollUiThread(new Criteria() {
+            @Override
+            public boolean isSatisfied() {
+                return mMostRecentActivity == null
+                        && (System.currentTimeMillis() - mTimeWhenSetToNullMillis)
+                        > TimeUnit.SECONDS.toMillis(1);

[dominickn, 2017/07/07 05:56:04]

Nit: possibly put the 1 as a static class level constant for clarity.

[piotrs, 2017/07/09 23:43:38]

Done.

+            }
+        });
+    }
 }