Allow the app banner installability check to run on page load.

chrome/browser/installable/installable_metrics.h

Index: chrome/browser/installable/installable_metrics.h
diff --git a/chrome/browser/installable/installable_metrics.h b/chrome/browser/installable/installable_metrics.h
new file mode 100644
index 0000000000000000000000000000000000000000..7d0e1b36c5d42f658f04fd5cd54d1a16633c7481
--- /dev/null
+++ b/chrome/browser/installable/installable_metrics.h
@@ -0,0 +1,26 @@
+// Copyright 2017 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.
+
+#ifndef CHROME_BROWSER_INSTALLABLE_INSTALLABLE_METRICS_H_
+#define CHROME_BROWSER_INSTALLABLE_INSTALLABLE_METRICS_H_
+
+class InstallableMetrics {
+ public:
+  // This enum backs a UMA histogram and must be treated as append-only.
+  enum InstallabilityCheckStatus {

[Ilya Sherman, 2017/03/31 17:03:15]

Optional nit: You can now use "enum class" without casts for recording UMA
histograms, so you might want to go ahead and do that here.

[dominickn, 2017/04/03 00:06:46]

Done. zomg no more static casting!!!!!

+    NOT_STARTED,
+    STOPPED_BEFORE_COMPLETION,
+    IN_PROGRESS_NON_PWA,

[Ilya Sherman, 2017/03/31 17:03:15]

nit: "PWA" is not an obvious acronym, at least for me.  I'd encourage you to
spell out something more complete here.

[dominickn, 2017/04/03 00:06:46]

Done.

+    IN_PROGRESS_PWA,
+    COMPLETE_NON_PWA,
+    COMPLETE_PWA,
+    MAX,

[Ilya Sherman, 2017/03/31 17:03:16]

Optional nit: I would name this "COUNT" -- "MAX" is usually used to semantically
refer to a value that's equal to the last "real" value in the enum.

[dominickn, 2017/04/03 00:06:46]

Done.

+  };
+
+  static void RecordMenuOpenHistogram(InstallabilityCheckStatus status);
+  static void RecordMenuItemAddToHomescreenHistogram(
+      InstallabilityCheckStatus status);
+};
+
+#endif  // CHROME_BROWSER_INSTALLABLE_INSTALLABLE_METRICS_H_