Add metrics for tracking how Chrome handled shortcut launches

chrome/browser/android/metrics/launch_metrics.cc

Index: chrome/browser/android/metrics/launch_metrics.cc
diff --git a/chrome/browser/android/metrics/launch_metrics.cc b/chrome/browser/android/metrics/launch_metrics.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5817261105980aa7e34c675756dd0aea3bf35ade
--- /dev/null
+++ b/chrome/browser/android/metrics/launch_metrics.cc
@@ -0,0 +1,40 @@
+// Copyright (c) 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.
+
+#include "chrome/browser/android/metrics/launch_metrics.h"
+
+#include "base/android/jni_string.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/metrics/user_metrics.h"
+#include "chrome/browser/metrics/rappor/sampling.h"
+#include "jni/LaunchMetrics_jni.h"
+#include "url/gurl.h"
+
+namespace metrics {
+
+enum HomeScreenLaunch {
+  HOME_SCREEN_LAUNCH_STANDALONE = 0,
+  HOME_SCREEN_LAUNCH_SHORTCUT = 1,
+  HOME_SCREEN_LAUNCH_COUNT = 2
+};
+
+bool RegisterLaunchMetrics(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+static void RecordLaunch(JNIEnv* env, jclass caller, jboolean standalone,
+                         jstring jurl) {
+  int action = standalone ? HOME_SCREEN_LAUNCH_STANDALONE
+                          : HOME_SCREEN_LAUNCH_SHORTCUT;
+  std::string rappor_metric = standalone ? "Launch.HomeScreen.Standalone"
+                                         : "Launch.HomeScreen.Shortcut";
+
+  UMA_HISTOGRAM_ENUMERATION("Launch.HomeScreen", action,
+                            HOME_SCREEN_LAUNCH_COUNT);
+
+  std::string url = base::android::ConvertJavaStringToUTF8(env, jurl);
+  rappor::SampleDomainAndRegistryFromGURL(rappor_metric, GURL(url));
+}
+
+};  // namespace metrics