[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..c887f5ae6170fa94711d8874e207de1276730e98 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";

[Peter Kasting, 2015/10/23 23:48:51]

Do you need these?  We try hard to avoid logging and it seems like this is the
sort of thing we shouldn't check in?

[apacible, 2015/10/24 22:06:28]

+imcheng: Do you remember our plans with the per-function logging here (and
elsewhere)?

[imcheng, 2015/10/26 17:18:14]

It helps with our debugging. Since it is only a DVLOG I feel it is fine to check
in for now, but once Media Router is in a more stable state then we can do a
cleanup to remove excessive logging.

+  const base::DictionaryValue* args_dict = nullptr;
+  int sink_count = -1;

[Peter Kasting, 2015/10/23 23:48:51]

Do you get a warning if you omit the initializers here?  If not, I'd omit them.

[apacible, 2015/10/24 22:06:28]

Done.

+  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) {