Add detailed histograms for navigator.share.

WebShare.ApiCount is needed (in addition to the existing use counter) to
get the total number of calls to the API, not de-duplicated per page
view.

BUG=636288

Review-Url: https://codereview.chromium.org/2228403002
Cr-Commit-Position: refs/heads/master@{#418760}

chrome/android/java/src/org/chromium/chrome/browser/webshare/ShareServiceImpl.java

@@ -8,6 +8,7 @@ import android.app.Activity;
 import android.content.ComponentName;
 import android.support.annotation.Nullable;
 
+import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.chrome.browser.share.ShareHelper;
 import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content_public.browser.WebContents;
@@ -23,6 +24,20 @@ import org.chromium.ui.base.WindowAndroid;
 public class ShareServiceImpl implements ShareService {
     private final Activity mActivity;
 
+    // These numbers are written to histograms. Keep in sync with WebShareMethod enum in
+    // histograms.xml, and don't reuse or renumber entries (except for the _COUNT entry).
+    private static final int WEBSHARE_METHOD_SHARE = 0;
+    // Count is technically 1, but recordEnumeratedHistogram requires a boundary of at least 2
+    // (https://crbug.com/645032).
+    private static final int WEBSHARE_METHOD_COUNT = 2;
+
+    // These numbers are written to histograms. Keep in sync with WebShareOutcome enum in
+    // histograms.xml, and don't reuse or renumber entries (except for the _COUNT entry).
+    private static final int WEBSHARE_OUTCOME_SUCCESS = 0;
+    private static final int WEBSHARE_OUTCOME_UNKNOWN_FAILURE = 1;
+    private static final int WEBSHARE_OUTCOME_CANCELED = 2;
+    private static final int WEBSHARE_OUTCOME_COUNT = 3;
+
     public ShareServiceImpl(@Nullable WebContents webContents) {
         mActivity = activityFromWebContents(webContents);
     }
@@ -35,17 +50,26 @@ public class ShareServiceImpl implements ShareService {
 
     @Override
     public void share(String title, String text, Url url, final ShareResponse callback) {
+        RecordHistogram.recordEnumeratedHistogram("WebShare.ApiCount", WEBSHARE_METHOD_SHARE,
+                WEBSHARE_METHOD_COUNT);
+
         if (mActivity == null) {
+            RecordHistogram.recordEnumeratedHistogram("WebShare.ShareOutcome",
+                    WEBSHARE_OUTCOME_UNKNOWN_FAILURE, WEBSHARE_OUTCOME_COUNT);
             callback.call("Share failed");
             return;
         }
 
         ShareHelper.TargetChosenCallback innerCallback = new ShareHelper.TargetChosenCallback() {
             public void onTargetChosen(ComponentName chosenComponent) {
+                RecordHistogram.recordEnumeratedHistogram("WebShare.ShareOutcome",
+                        WEBSHARE_OUTCOME_SUCCESS, WEBSHARE_OUTCOME_COUNT);
                 callback.call(null);
             }
 
             public void onCancel() {
+                RecordHistogram.recordEnumeratedHistogram("WebShare.ShareOutcome",
+                        WEBSHARE_OUTCOME_CANCELED, WEBSHARE_OUTCOME_COUNT);
                 callback.call("Share canceled");
             }
         };

tools/metrics/histograms/histograms.xml

@@ -68988,6 +68988,28 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Time for capturing one frame in window capturing.</summary>
 </histogram>
 
+<histogram name="WebShare.ApiCount" enum="WebShareMethod">
+  <owner>mgiuca@chromium.org</owner>
+  <summary>
+    Counts the number of calls to navigator.share. Includes both successful and
+    failed shares.
+  </summary>
+</histogram>
+
+<histogram name="WebShare.ShareOutcome" enum="WebShareOutcome">
+  <owner>mgiuca@chromium.org</owner>
+  <summary>
+    Records the outcome of calls to navigator.share. This will not count any
+    calls that never complete (e.g., if the page closes while the picker is
+    open). Therefore, DO NOT look at the raw percentages of this histogram;
+    instead, compare these numbers with the WebShare.ApiCount.Share total.
+
+    NOTE: At the moment, if the user cancels the picker, its recording will be
+    delayed, and possibly never recorded (https://crbug.com/636274), so that
+    will account for a discrepancy between ShareOutcome and ApiCount.Share.
+  </summary>
+</histogram>
+
 <histogram name="WebsiteSettings.Action" enum="WebsiteSettingsAction">
   <owner>lgarron@chromium.org</owner>
   <summary>
@@ -98915,6 +98937,16 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="3" label="H264"/>
 </enum>
 
+<enum name="WebShareMethod" type="int">
+  <int value="0" label="Share"/>
+</enum>
+
+<enum name="WebShareOutcome" type="int">
+  <int value="0" label="Success"/>
+  <int value="1" label="UnknownFailure"/>
+  <int value="2" label="Canceled"/>
+</enum>
+
 <enum name="WebsiteSettingsAction" type="int">
   <int value="0" label="Opened"/>
   <int value="1" label="Selected Permissions tab"/>