Add desktop engagement metrics.

chrome/browser/chrome_browser_main.cc

Index: chrome/browser/chrome_browser_main.cc
diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index a93e7fc9b0ab471f5568e8b38c206742dc1db617..4d1d142ffd39f5fb47cd9429580f52f9d3b344e0 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -267,6 +267,10 @@
 #include "services/shell/runner/common/client_util.h"
 #endif
 
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+#include "chrome/browser/metrics/desktop_engagement/desktop_engagement_service.h"

[Lei Zhang, 2016/08/01 17:29:02]

Just put this with the !OS_ANDROID #includes on line 260? (There's no / barely
any iOS in chrome/)

[gayane -on leave until 09-2017, 2016/08/02 17:13:44]

how about ChromeOS, this shouldn't work for ChromeOS either

[Lei Zhang, 2016/08/02 17:31:50]

So "desktop" in my mind includes ChromeOS, and https://crbug.com/615080 is
marked as Win/Mac/Linux/CrOS.

Still don't want ChromeOS? If that's the case, then you need to explicitly check
that OS_CHROMEOS is not defined, because OS_LINUX is defined on ChromeOS.

+#endif
+
 using content::BrowserThread;
 
 namespace {
@@ -790,6 +794,10 @@ void ChromeBrowserMainParts::SetupMetricsAndFieldTrials() {
   // that was already chosen.
   sampling_profiler_config_.RegisterSyntheticFieldTrial();
 
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+  metrics::DesktopEngagementService::Initialize();
+#endif
+
 #if defined(OS_WIN)
   chrome_browser::SetupPreReadFieldTrial();
 #endif  // defined(OS_WIN)