Add UMA and Rappor metrics to capture URLs passed in at startup.

chrome/browser/ui/startup/startup_browser_creator_impl.cc

Index: chrome/browser/ui/startup/startup_browser_creator_impl.cc
diff --git a/chrome/browser/ui/startup/startup_browser_creator_impl.cc b/chrome/browser/ui/startup/startup_browser_creator_impl.cc
index 7daf465e1e645f127adc8e255a8a264e69fbc751..8bb408f57c16bc521517ca37f20d2f45f8d9adbe 100644
--- a/chrome/browser/ui/startup/startup_browser_creator_impl.cc
+++ b/chrome/browser/ui/startup/startup_browser_creator_impl.cc
@@ -16,7 +16,7 @@
 #include "base/environment.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_number_conversions.h"
@@ -79,6 +79,7 @@
 #include "chrome/grit/locale_settings.h"
 #include "chrome/installer/util/browser_distribution.h"
 #include "components/google/core/browser/google_util.h"
+#include "components/rappor/rappor_utils.h"
 #include "content/public/browser/child_process_security_policy.h"
 #include "content/public/browser/dom_storage_context.h"
 #include "content/public/browser/notification_observer.h"
@@ -325,6 +326,10 @@ bool StartupBrowserCreatorImpl::Launch(Profile* profile,
                                        const std::vector<GURL>& urls_to_open,
                                        bool process_startup,
                                        chrome::HostDesktopType desktop_type) {
+  UMA_HISTOGRAM_COUNTS_100("Startup.BrowserLaunchURLCount",
+                           urls_to_open.size());

[Peter Kasting, 2015/08/12 22:28:23]

Nit: To avoid a (currently disabled) warning on MSVC< you should probably pass:

static_cast<base::HistogramBase::Sample>(urls_to_open.size())

[rkaplow, 2015/08/12 22:37:40]

The current convention for this macro is just a number. I would think it would
make sense to switch them all at once (if we want to do this) instead of
piecemeal.

Let me know if that is ok.

[Peter Kasting, 2015/08/12 22:46:11]

I'm not sure if I'm being clear.  Passing a number is fine.  Passing a variable
is fine if the variable can be losslessly converted to Sample (which is a
typedef for int32).  The problem is that you're passing a size_t, which is not
guaranteed to fit in an int32, and that will trigger the warning.  Hence the
cast.

Few histogram callers pass size_ts, so this cast is rarely needed.  So this
isn't a matter of trying to systematically change something throughout the
codebase.

[rkaplow, 2015/08/13 02:11:58]

Ah thanks, that makes sense.

+  RecordRapporOnStartupURLs(urls_to_open);
+
   DCHECK(profile);
   profile_ = profile;
 
@@ -1015,3 +1020,11 @@ void StartupBrowserCreatorImpl::InitializeWelcomeRunType(
     welcome_run_type_ = WelcomeRunType::FIRST_RUN_LAST_TAB;
 #endif  // !OS_WIN
 }
+
+void StartupBrowserCreatorImpl::RecordRapporOnStartupURLs(
+    const std::vector<GURL>& urls_to_open) {
+  for (const GURL& url : urls_to_open) {
+    rappor::SampleDomainAndRegistryFromGURL(g_browser_process->rappor_service(),
+                                            "Startup.BrowserLaunchURL", url);
+  }
+}