Report histogram creation results.

content/app/content_main_runner.cc

Index: content/app/content_main_runner.cc
diff --git a/content/app/content_main_runner.cc b/content/app/content_main_runner.cc
index ba10cbb430c1d557b2521473079b6ead49cb6fd1..797390fa0d8b0366e638b83432c2f99f201fc79c 100644
--- a/content/app/content_main_runner.cc
+++ b/content/app/content_main_runner.cc
@@ -23,6 +23,7 @@
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
+#include "base/metrics/histogram_base.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/path_service.h"
 #include "base/process/launch.h"
@@ -30,6 +31,7 @@
 #include "base/process/process_handle.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
@@ -752,6 +754,11 @@ class ContentMainRunnerImpl : public ContentMainRunner {
     std::string process_type =
         command_line.GetSwitchValueASCII(switches::kProcessType);
 
+    base::StringPiece report_type = process_type;
+    if (report_type.empty())
+      report_type = "browser";

[Alexei Svitkine (slow), 2016/03/01 16:41:34]

Is this really "browser"? Seems like this is assuming something about the user
of the content/ API which is not necessarily true.

[bcwhite, 2016/03/02 19:14:19]

If the process is called without a "--type=" parameter then it launches the
browser which then re-launches itself with that parameter to start renderers,
gpu process, and potentially others.

With the change to histogram_suffixes, though, there needs to be an empty name
anyway so this can go away.

+    base::HistogramBase::EnableCreationReportHistogram(report_type);
+
     MainFunctionParams main_params(command_line);
     main_params.ui_task = ui_task_;
 #if defined(OS_WIN)