Observe input metrics from web content area.

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 3a3df1e2ec3be29174dddfb728eaebfe9c0e1c5b..f00089e70e819fe4cae8da263d7d7aa5b50498d5 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_service.h"
+#endif
+
 using content::BrowserThread;
 
 namespace {
@@ -786,6 +790,11 @@ void ChromeBrowserMainParts::SetupMetricsAndFieldTrials() {
   // that was already chosen.
   sampling_profiler_config_.RegisterSyntheticFieldTrial();
 
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+  // Start the DesktopEngagementService.
+  DesktopEngagementService::Initialize();
+#endif  // defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+
 #if defined(OS_WIN)
   chrome_browser::SetupPreReadFieldTrial();
 #endif  // defined(OS_WIN)