[Media Router] Add P1 UMA metrics for Media Router.

chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc

Index: chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc
diff --git a/chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc b/chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc
index 3c44c1c3c9f8dad1fb056bdeeb6e5f2ccc14bbe7..d3c0d1f5a63b79c28a2e7a2c946c6b559c399c5d 100644
--- a/chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc
+++ b/chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc
@@ -7,6 +7,7 @@
 #include <string>
 
 #include "base/bind.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/media/router/issue.h"
 #include "chrome/browser/ui/webui/media_router/media_router_ui.h"
@@ -27,6 +28,7 @@ const char kCreateRoute[] = "requestRoute";
 const char kActOnIssue[] = "actOnIssue";
 const char kCloseRoute[] = "closeRoute";
 const char kCloseDialog[] = "closeDialog";
+const char kReportSinkCount[] = "reportSinkCount";
 
 // JS function names.
 const char kSetInitialData[] = "media_router.ui.setInitialData";
@@ -207,6 +209,9 @@ void MediaRouterWebUIMessageHandler::OnCreateRouteResponseReceived(
                                      base::StringValue(sink_id),
                                      *base::Value::CreateNullValue());
   }
+
+  UMA_HISTOGRAM_BOOLEAN(
+      "MediaRouter.Ui.Action.StartLocalSessionSuccessful", route);
 }
 
 void MediaRouterWebUIMessageHandler::UpdateIssue(const Issue* issue) {
@@ -246,6 +251,10 @@ void MediaRouterWebUIMessageHandler::RegisterMessages() {
       kCloseDialog,
       base::Bind(&MediaRouterWebUIMessageHandler::OnCloseDialog,
                  base::Unretained(this)));
+  web_ui()->RegisterMessageCallback(
+      kReportSinkCount,
+      base::Bind(&MediaRouterWebUIMessageHandler::OnReportSinkCount,
+                 base::Unretained(this)));
 }
 
 void MediaRouterWebUIMessageHandler::OnRequestInitialData(
@@ -373,6 +382,19 @@ void MediaRouterWebUIMessageHandler::OnCloseDialog(
   media_router_ui_->Close();
 }
 
+void MediaRouterWebUIMessageHandler::OnReportSinkCount(
+    const base::ListValue* args) {
+  DVLOG(1) << "OnReportSinkCount";
+  const base::DictionaryValue* args_dict;
+  int sink_count;
+  if (!args->GetDictionary(0, &args_dict) ||
+      !args_dict->GetInteger("sinkCount", &sink_count)) {
+    DVLOG(1) << "Unable to extract args.";
+    return;
+  }
+  UMA_HISTOGRAM_COUNTS_100("MediaRouter.Ui.Device.Count", sink_count);
+}
+
 bool MediaRouterWebUIMessageHandler::ActOnIssueType(
     const IssueAction::Type& action_type,
     const base::DictionaryValue* args) {