mash: Add SystemTrayClient interface, use to show date settings

ash/mus/system_tray_delegate_mus.cc

Index: ash/mus/system_tray_delegate_mus.cc
diff --git a/ash/mus/system_tray_delegate_mus.cc b/ash/mus/system_tray_delegate_mus.cc
index 8add535aa2bf63f0e61f51d57121d91a21396604..ad729a4dbbdbea3d8476cc8ff8b601f644bbc3b2 100644
--- a/ash/mus/system_tray_delegate_mus.cc
+++ b/ash/mus/system_tray_delegate_mus.cc
@@ -8,6 +8,7 @@
 #include "ash/common/wm_shell.h"
 #include "base/i18n/time_formatting.h"
 #include "base/logging.h"
+#include "services/shell/public/cpp/connector.h"
 
 namespace ash {
 namespace {
@@ -16,8 +17,13 @@ SystemTrayDelegateMus* g_instance = nullptr;
 
 }  // namespace
 
-SystemTrayDelegateMus::SystemTrayDelegateMus()
-    : hour_clock_type_(base::GetHourClockType()) {
+SystemTrayDelegateMus::SystemTrayDelegateMus(shell::Connector* connector)
+    : connector_(connector),
+      hour_clock_type_(base::GetHourClockType()),
+      weak_factory_(this) {
+  DCHECK(connector_);
+  // Don't make an initial connection to exe:chrome. Do it on demand.
+
   DCHECK(!g_instance);
   g_instance = this;
 }
@@ -32,10 +38,33 @@ SystemTrayDelegateMus* SystemTrayDelegateMus::Get() {
   return g_instance;
 }
 
+void SystemTrayDelegateMus::ConnectToSystemTrayClient() {
+  // Check if already connected.

[sky, 2016/09/26 15:23:14]

optional: IMO this comment and 43 document exactly what the code does and don't
provide much value.

[James Cook, 2016/09/26 18:01:37]

Removed this one and the one on line 46.

+  if (system_tray_client_.is_bound())
+    return;
+
+  // Connect to chrome browser.
+  connector_->ConnectToInterface("exe:chrome", &system_tray_client_);

[sky, 2016/09/26 15:23:14]

What you have here certainly works. Consider though that one nice thing about
the explicit SetClient call you had before is that it means ash doesn't care who
is providing the client interface and doesn't need to establish an out bound
connection like this.

[James Cook, 2016/09/26 18:01:37]

As discussed offline, keeping this so commands on the system_tray_client_
interface get queued if the user takes an action before chrome is up.

+
+  // Tolerate chrome crashing and coming back up.
+  system_tray_client_.set_connection_error_handler(
+      base::Bind(&SystemTrayDelegateMus::OnClientConnectionError,
+                 weak_factory_.GetWeakPtr()));

[sky, 2016/09/26 15:23:14]

As this owns system_tray_client_ you shouldn't need a weakptr here.

[James Cook, 2016/09/26 18:01:37]

Done.

+}
+
+void SystemTrayDelegateMus::OnClientConnectionError() {
+  system_tray_client_.reset();
+}
+
 base::HourClockType SystemTrayDelegateMus::GetHourClockType() const {
   return hour_clock_type_;
 }
 
+void SystemTrayDelegateMus::ShowDateSettings() {
+  ConnectToSystemTrayClient();
+  system_tray_client_->ShowDateSettings();
+}
+
 void SystemTrayDelegateMus::SetUse24HourClock(bool use_24_hour) {
   hour_clock_type_ = use_24_hour ? base::k24HourClock : base::k12HourClock;
   WmShell::Get()->system_tray_notifier()->NotifyDateFormatChanged();