Log some information about the state of the homepage on Android.

chrome/android/java/src/org/chromium/chrome/browser/DeferredStartupHandler.java

Index: chrome/android/java/src/org/chromium/chrome/browser/DeferredStartupHandler.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/DeferredStartupHandler.java b/chrome/android/java/src/org/chromium/chrome/browser/DeferredStartupHandler.java
index 3eab85dd886007b5d92e66de7ebbc18443157588..892870c296b4ff5ea8ff6fb3871428a7fa58bb62 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/DeferredStartupHandler.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/DeferredStartupHandler.java
@@ -21,7 +21,10 @@ import org.chromium.chrome.browser.crash.CrashFileManager;
 import org.chromium.chrome.browser.crash.MinidumpUploadService;
 import org.chromium.chrome.browser.media.MediaCaptureNotificationService;
 import org.chromium.chrome.browser.metrics.UmaUtils;
+import org.chromium.chrome.browser.ntp.NewTabPage;
 import org.chromium.chrome.browser.partnerbookmarks.PartnerBookmarksShim;
+import org.chromium.chrome.browser.partnercustomizations.HomepageManager;
+import org.chromium.chrome.browser.partnercustomizations.PartnerBrowserCustomizations;
 import org.chromium.chrome.browser.physicalweb.PhysicalWeb;
 import org.chromium.chrome.browser.precache.PrecacheLauncher;
 import org.chromium.chrome.browser.preferences.ChromePreferenceManager;
@@ -106,6 +109,29 @@ public class DeferredStartupHandler {
 
         AfterStartupTaskUtils.setStartupComplete();
 
+        // Log details about the current state of the homepage.  On other platforms, this
+        // information is stored as part of Chrome preferences. But on Android, an external
+        // provider must be contacted before we can fully resolve this.  Also, we do not store

[Mark P, 2016/05/24 04:31:26]

please rewrite this sentence without "we"--it's unclear who "we" refers to here
(Android? Chrome? Chrome for Android code?)

[Ted C, 2016/05/24 16:53:15]

removed this comment entirely as it is documented in native

+        // this information as part of Chrome preferences because we never want this to be synced
+        // across devices.  See PrefMetricsService::RecordLaunchPrefs for the inspiration for these
+        // metrics.
+        PartnerBrowserCustomizations.setOnInitializeAsyncFinished(new Runnable() {

[Mark P, 2016/05/24 04:31:26]

Will this be logged on startup (well technically profile open) like the regular
Chrome logging? i.e, the same frequency / trigger?

[Ted C, 2016/05/24 16:53:15]

It will be logged once on startup.  No multi-profile support.  The main this
this location ensures is that it will not be overlogged since we trigger new
Chrome activities fairly often for different use cases.

This will be called at most a single time for each browser process start.

+            @Override
+            public void run() {
+                boolean isHomepageEnabled =
+                        HomepageManager.isHomepageEnabled(application);
+                RecordHistogram.recordBooleanHistogram(
+                        "Settings.ShowHomeButton", isHomepageEnabled);

[Mark P, 2016/05/24 04:31:26]

Does show home button really mean the same thing as home page is enabled?!
I would think (without researching the code) the latter has to do with starting
up with a home page...

[Ted C, 2016/05/24 16:53:15]

Nah, isHomepageEnabled is what we use for button state.  It means there is an
external provider on the device and the user has not turned it off in
preferences (the preferences is only exposed if there is an external provider).

+
+                if (!isHomepageEnabled) return;
+
+                String homepageUrl = HomepageManager.getHomepageUri(application);
+                RecordHistogram.recordBooleanHistogram(
+                        "Settings.GivenShowHomeButton_HomePageIsNewTabPage",
+                        NewTabPage.isNTPUrl(homepageUrl));
+            }
+        });
+
         // TODO(aruslan): http://b/6397072 This will be moved elsewhere
         PartnerBookmarksShim.kickOffReading(application);