Flapper field trial to use workerpool for sync file operations.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index ca44da389ee4c2cdd89b41ec8371533b1ad502b3..9fe1b2960829cc718766a2a168d6987abf87b710 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "base/command_line.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/stats_counters.h"
 #include "base/string16.h"
@@ -2333,6 +2334,22 @@ void WebContentsImpl::OnSetSelectedColorInColorChooser(int color_chooser_id,
 void WebContentsImpl::OnPepperPluginHung(int plugin_child_id,
                                          const FilePath& path,
                                          bool is_hung) {
+  HISTOGRAM_COUNTS("Pepper.PluginHung", 1);
+
+  // Determine how often hangs happen when using worker pool versus
+  // FILE thread.  kFieldTrialName needs to match the value in
+  // pepper_file_message_filter.cc, but plumbing that through would be
+  // disruptive for temporary code.
+  // TODO(shess): Remove once the workpool is proven superior.
+  // http://crbug.com/153383
+  static const char* const kFieldTrialName = "FlapperIOThread";
+  static const bool hung_trial_exists =
+      base::FieldTrialList::TrialExists(kFieldTrialName);
+  if (hung_trial_exists) {
+    HISTOGRAM_COUNTS(base::FieldTrial::MakeName("Pepper.PluginHung",
+                                                kFieldTrialName), 1);
+  }
+
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
                     PluginHungStatusChanged(plugin_child_id, path, is_hung));
 }