Add metrics for tracking how Chrome handled shortcut launches

chrome/android/java/src/org/chromium/chrome/browser/metrics/LaunchMetrics.java

Index: chrome/android/java/src/org/chromium/chrome/browser/metrics/LaunchMetrics.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/metrics/LaunchMetrics.java b/chrome/android/java/src/org/chromium/chrome/browser/metrics/LaunchMetrics.java
new file mode 100644
index 0000000000000000000000000000000000000000..d3e66ef4acbed8639c73acde69795af526590d88
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/metrics/LaunchMetrics.java
@@ -0,0 +1,53 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.metrics;
+
+import org.chromium.base.JNINamespace;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Used for recording metrics about Chrome launches.
+ */
+@JNINamespace("metrics")
+public class LaunchMetrics {

[Ted C, 2015/03/06 21:12:48]

Should this be HomescreenLaunchMetrics?

This name seems very generic and the recordStandaloneActivityLaunch seems like
it could apply to external intents coming from gmail for example.  I think we
need to clarify "somehow" that this is for tracking things the user has added to
the homescreen (whether it be a webapp shortcut or a bookmark link).

And with that said, do we track the add to homescreen as a bookmark differently
than we track if the user added a bookmark shortcut widget themselves?

[gone, 2015/03/06 22:14:09]

I was kind of hoping to move that stuff from IntentHandler into here later,
actually
(IntentHandler.ExternalAppId, IntentHandler.determineExternalIntentSource,
IntentHandler.recordExternalIntentSourceUMA, etc).  It's not required for the
bug, yet,
though, and will make it harder to make a cherry-pick.

Clarified with Owen; we're lumping all home screen bookmarks all together.

+    private static final List<String> sActivityUrls = new ArrayList<String>();
+    private static final List<String> sTabUrls = new ArrayList<String>();
+
+    /**
+     * Records the launch of a standalone Activity for a URL (i.e. a WebappActivity).
+     * @param url URL that kicked off the Activity's creation.
+     */
+    public static void recordStandaloneActivityLaunch(String url) {
+        sActivityUrls.add(url);
+    }
+
+    /**
+     * Records the launch of a Tab for a URL (i.e. a Home screen shortcut).
+     * @param url URL that kicked off the Tab's creation.
+     */
+    public static void recordShortcutLaunch(String url) {
+        sTabUrls.add(url);
+    }
+
+    /**
+     * Calls out to native code to record URLs that have been launched via the Home screen.
+     * This intermediate step is necessary because Activity.onCreate() may be called when
+     * the native library has not yet been loaded.
+     */
+    public static void commitLaunchMetrics() {
+        for (String url : sActivityUrls) {
+            nativeRecordLaunch(true, url);
+        }
+        for (String url : sTabUrls) {
+            nativeRecordLaunch(false, url);
+        }
+        sActivityUrls.clear();
+        sTabUrls.clear();
+    }
+
+    private static native void nativeRecordLaunch(boolean standalone, String url);
+}