Add metrics to track Google Play install WebAPK failures.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/metrics/WebApkUma.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/metrics/WebApkUma.java b/chrome/android/java/src/org/chromium/chrome/browser/metrics/WebApkUma.java
index b91d1adc614e78ec0908c40a226aecd032f54c07..964b6ebfd409b2183a601b742d9e7377400df376 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/metrics/WebApkUma.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/metrics/WebApkUma.java
@@ -24,11 +24,28 @@ public class WebApkUma {
     public static final int UPDATE_REQUEST_QUEUED_THREE_TIMES = 2;
     public static final int UPDATE_REQUEST_QUEUED_MAX = 3;
 
+    // This enum is used to back UMA histograms, and should therefore be treated as append-only.
+    public static final int GOOGLE_PLAY_INSTALL_SUCCESS = 0;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_NO_DELEGATE = 1;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_TO_CONNECT_TO_SERVICE = 2;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_CALLER_VERIFICATION_FAILURE = 3;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_POLICY_VIOLATION = 4;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_API_DISABLED = 5;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_REQUEST_FAILED = 6;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_DOWNLOAD_CANCELLED = 7;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_DOWNLOAD_ERROR = 8;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_INSTALL_ERROR = 9;
+    public static final int GOOGLE_PLAY_INSTALL_FAILED_INSTALL_TIMEOUT = 10;
+    public static final int GOOGLE_PLAY_INSTALL_RESULT_MAX = 11;
+
     public static final String HISTOGRAM_UPDATE_REQUEST_SENT =
             "WebApk.Update.RequestSent";
 
     public static final String HISTOGRAM_UPDATE_REQUEST_QUEUED = "WebApk.Update.RequestQueued";
 
+    public static final String HISTOGRAM_GOOGLE_PLAY_INSTALL_RESULT =
+            "WebApk.Install.GooglePlayInstallResult";
+
     private static final int WEBAPK_OPEN_MAX = 3;
     public static final int WEBAPK_OPEN_LAUNCH_SUCCESS = 0;
     public static final int WEBAPK_OPEN_NO_LAUNCH_INTENT = 1;
@@ -63,4 +80,14 @@ public class WebApkUma {
         assert type >= 0 && type < WEBAPK_OPEN_MAX;
         RecordHistogram.recordEnumeratedHistogram("WebApk.OpenFromMenu", type, WEBAPK_OPEN_MAX);
     }
+
+    /**
+     * Records whether installing WebAPKs from Google Play succeeded. If not, records the reason of
+     * failures sent by Google Play.

[pkotwicz, 2017/03/21 16:59:39]

Nit: "the reason of failures" -> "the failure reason"

"the reason that the install failed" is also OK

[Xi Han, 2017/03/21 18:43:45]

Done.

+     */
+    public static void recordGooglePlayIntallResult(int result) {
+        assert result >= 0 && result < GOOGLE_PLAY_INSTALL_RESULT_MAX;
+        RecordHistogram.recordEnumeratedHistogram(
+                HISTOGRAM_GOOGLE_PLAY_INSTALL_RESULT, result, GOOGLE_PLAY_INSTALL_RESULT_MAX);

[pkotwicz, 2017/03/21 16:59:39]

Nit: You can just inline the histogram name
("WebApk.Install.GooglePlayInstallResult")

[Xi Han, 2017/03/21 18:43:45]

Done.

+    }
 }