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..e1a4e1b5aababdd79cf4f29472a48207532f380d
--- /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 {
+    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 recordHomeScreenLaunchIntoStandaloneActivity(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 recordHomeScreenLaunchIntoTab(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);
+}