customtabs: Histograms for special sessions prerendering.

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java

Index: chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
index a8df5211de0d040a2abf091b6cd20d2de820fde3..619681a0d662a373970ffcef80085cc5a73a55d7 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
@@ -33,6 +33,7 @@ import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.SuppressFBWarnings;
 import org.chromium.base.library_loader.ProcessInitException;
+import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ChromeApplication;
 import org.chromium.chrome.browser.IntentHandler;
@@ -459,13 +460,19 @@ public class CustomTabsConnection {
         boolean urlsMatch = TextUtils.equals(prerenderedUrl, url)
                 || (ignoreFragments
                         && UrlUtilities.urlsMatchIgnoringFragments(prerenderedUrl, url));
+        WebContents result = null;
         if (urlsMatch && TextUtils.equals(prerenderReferrer, referrer)) {
+            result = webContents;
             mPrerender = null;
-            return webContents;
         } else {
             cancelPrerender(session);
         }
-        return null;
+        if (mClientManager.isSpecialSession(session) && webContents != null) {

[Yusuf, 2016/08/01 20:34:38]

Nonstandard? Or have a call that says isStandard and only record the values as
non-standard?

I kinda agree that special is not the best word here.

[Benoit L, 2016/08/02 16:10:24]

Done.

+            RecordHistogram.recordBooleanHistogram(
+                    "CustomTabs.SpecialSessionPrerenderMatched", result != null);
+        }
+
+        return result;
     }
 
     /** Returns the URL prerendered for a session, or null. */
@@ -729,6 +736,10 @@ public class CustomTabsConnection {
         if (webContents == null) return false;
         if (throttle) mClientManager.registerPrerenderRequest(uid, url);
         mPrerender = new PrerenderedUrlParams(session, webContents, url, referrer, extras);
+
+        RecordHistogram.recordBooleanHistogram(
+                "CustomTabs.PrerenderSessionIsSpecial", mClientManager.isSpecialSession(session));
+
         return true;
     }