Record how often we end up in Chrome from external navigations.

chrome/android/java/src/org/chromium/chrome/browser/IntentHandler.java

Index: chrome/android/java/src/org/chromium/chrome/browser/IntentHandler.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/IntentHandler.java b/chrome/android/java/src/org/chromium/chrome/browser/IntentHandler.java
index 993061d5a575feb8e8fb3b12982f7f2dde38a2d5..afd17eaf3a0aa6e4debc432ec5454231a68a14ac 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/IntentHandler.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/IntentHandler.java
@@ -23,10 +23,12 @@ import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.Log;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.metrics.RecordHistogram;
+import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.chrome.browser.externalauth.ExternalAuthUtils;
 import org.chromium.chrome.browser.externalnav.ExternalNavigationDelegateImpl;
 import org.chromium.chrome.browser.externalnav.IntentWithGesturesHandler;
 import org.chromium.chrome.browser.omnibox.AutocompleteController;
+import org.chromium.chrome.browser.rappor.RapporServiceBridge;
 import org.chromium.chrome.browser.search_engines.TemplateUrlService;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.document.ActivityDelegate;
@@ -133,6 +135,12 @@ public class IntentHandler {
     public static final String EXTRA_WINDOW_ID = "org.chromium.chrome.browser.window_id";
 
     /**
+     * Records package names of other applications in the system that could have handled
+     * this intent.
+     */
+    public static final String EXTRA_EXTERNAL_NAV_PACKAGES = "org.chromium.chrome.browser.eenp";
+
+    /**
      * Fake ComponentName used in constructing TRUSTED_APPLICATION_CODE_EXTRA.
      */
     private static ComponentName sFakeComponentName = null;
@@ -289,6 +297,17 @@ public class IntentHandler {
                 externalId.ordinal(), ExternalAppId.INDEX_BOUNDARY.ordinal());
     }
 
+    private void recordChromeIntentPackageHandlers(Intent intent) {

[gone, 2016/06/29 16:30:44]

Private, but add a javadoc saying exactly what this records?  Alternatively,
rename this function?  I don't know why "Chrome" is in the title given what's
being recorded.

recordPackageHandlersForIntentDeliveredToChrome()?

+        List<String> packages = IntentUtils.safeGetStringArrayListExtra(intent,
+                IntentHandler.EXTRA_EXTERNAL_NAV_PACKAGES);
+        if (packages != null) {
+            RecordUserAction.record("MobileExternalNavigationReceived");
+            for (String name : packages) {
+                RapporServiceBridge.sampleString("Android.ExternalNavigationNotChosen", name);
+            }
+        }
+    }
+
     /**
      * Handles an Intent after the ChromeTabbedActivity decides that it shouldn't ignore the
      * Intent.
@@ -316,6 +335,7 @@ public class IntentHandler {
                 IntentUtils.safeGetStringExtra(intent, Browser.EXTRA_APPLICATION_ID),
                 tabIdToBringToFront, hasUserGesture, intent);
         recordExternalIntentSourceUMA(intent);
+        recordChromeIntentPackageHandlers(intent);
         return true;
     }