Adds Histogram to Count Uses of Home Button to non-Chrome Pages

i.e., allows counting of home button uses that lead to places
besides, say, the new tab page.

Right now all home button uses are logged as a user action "Home"
and it's a pain to try to figure out based on other UMA histograms
whether the home button leads to the new tab page or some web page.
This makes it easier.

Bug: 953445
Change-Id: I2ad455af3b6bd8884813186a1f54ebaa244b2c73
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1609973Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Reviewed-by: Pedro Amaral <amaralp@chromium.org>
Commit-Queue: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660058}

chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarManager.java

@@ -113,6 +113,7 @@ import org.chromium.content_public.browser.NavigationEntry;
 import org.chromium.content_public.browser.NavigationHandle;
 import org.chromium.content_public.browser.UiThreadTaskTraits;
 import org.chromium.content_public.browser.WebContents;
+import org.chromium.content_public.common.ContentUrlConstants;
 import org.chromium.ui.base.DeviceFormFactor;
 import org.chromium.ui.base.PageTransition;
 import org.chromium.ui.widget.Toast;
@@ -1455,6 +1456,12 @@ public class ToolbarManager implements ScrimObserver, ToolbarTabController, UrlF
         if (TextUtils.isEmpty(homePageUrl) || isNewTabPageButtonEnabled) {
             homePageUrl = UrlConstants.NTP_URL;
         }
+        boolean is_chrome_internal =
+                homePageUrl.startsWith(ContentUrlConstants.ABOUT_URL_SHORT_PREFIX)
+                || homePageUrl.startsWith(UrlConstants.CHROME_URL_SHORT_PREFIX)
+                || homePageUrl.startsWith(UrlConstants.CHROME_NATIVE_URL_SHORT_PREFIX);
+        RecordHistogram.recordBooleanHistogram(
+                "Navigation.Home.IsChromeInternal", is_chrome_internal);
         if (isNewTabPageButtonEnabled) {
             recordToolbarUseForIPH(EventConstants.CLEAR_TAB_BUTTON_CLICKED);
         } else {

chrome/browser/ui/browser_commands.cc

@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "base/command_line.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/user_metrics.h"
 #include "base/strings/utf_string_conversions.h"
@@ -61,6 +62,7 @@
 #include "chrome/common/chrome_features.h"
 #include "chrome/common/content_restriction.h"
 #include "chrome/common/pref_names.h"
+#include "chrome/common/url_constants.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/bookmarks/browser/bookmark_utils.h"
 #include "components/bookmarks/common/bookmark_pref_names.h"
@@ -96,6 +98,7 @@
 #include "ui/base/clipboard/scoped_clipboard_writer.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 #include "url/gurl.h"
+#include "url/url_constants.h"
 
 #if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "chrome/browser/extensions/api/commands/command_service.h"
@@ -533,6 +536,11 @@ void Home(Browser* browser, WindowOpenDisposition disposition) {
     extensions::MaybeShowExtensionControlledHomeNotification(browser);
 #endif
 
+  bool is_chrome_internal = url.SchemeIs(url::kAboutScheme) ||
+                            url.SchemeIs(content::kChromeUIScheme) ||
+                            url.SchemeIs(chrome::kChromeNativeScheme);
+  base::UmaHistogramBoolean("Navigation.Home.IsChromeInternal",
+                            is_chrome_internal);
   OpenURLParams params(
       url, Referrer(), disposition,
       ui::PageTransitionFromInt(ui::PAGE_TRANSITION_AUTO_BOOKMARK |

tools/metrics/histograms/histograms.xml

@@ -62428,6 +62428,19 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="Navigation.Home.IsChromeInternal" enum="Boolean"
+    expires_after="2020-05-08">
+  <owner>mpearson@chromium.org</owner>
+  <owner>amaralp@chromium.org</owner>
+  <summary>
+    Emitted every time a user uses a Home button to go to their home page.
+    Records whether the page is chrome-internal (most likely the New Tab Page or
+    about:blank) or not (most likely an actual web site). For the purpose of
+    this histogram, about:, chrome: and chrome-native: are considered
+    chrome-internal; everything else is not.
+  </summary>
+</histogram>
+
 <histogram name="Navigation.Intercept.Ignored" enum="Boolean">
   <owner>csharrison@chromium.org</owner>
   <summary>