Consolidate volume control code.

ash/system/tray/system_tray_unittest.cc

Index: ash/system/tray/system_tray_unittest.cc
diff --git a/ash/system/tray/system_tray_unittest.cc b/ash/system/tray/system_tray_unittest.cc
index b03c548a14ff0f405661e05fafa812349dd31fc6..28aaa8ae2da0675a7bc3a9b881c01b12af5c53fc 100644
--- a/ash/system/tray/system_tray_unittest.cc
+++ b/ash/system/tray/system_tray_unittest.cc
@@ -6,6 +6,8 @@
 
 #include <vector>
 
+#include "ash/accelerators/accelerator_controller.h"
+#include "ash/volume_control_delegate.h"
 #include "ash/system/status_area_widget.h"
 #include "ash/system/tray/system_tray_item.h"
 #include "ash/test/ash_test_base.h"
@@ -87,9 +89,56 @@ class TestItem : public SystemTrayItem {
   views::View* notification_view_;
 };
 
+class DummyVolumeControlDelegate : public VolumeControlDelegate {
+ public:
+  explicit DummyVolumeControlDelegate() {}
+  virtual ~DummyVolumeControlDelegate() {}
+
+  virtual bool HandleVolumeMute(const ui::Accelerator& accelerator) OVERRIDE {
+    return true;
+  }
+  virtual bool HandleVolumeDown(const ui::Accelerator& accelerator) OVERRIDE {
+    return true;
+  }
+  virtual bool HandleVolumeUp(const ui::Accelerator& accelerator) OVERRIDE {
+    return true;
+  }
+  virtual void SetVolumePercent(double percent) OVERRIDE {
+  }
+  virtual bool IsAudioMuted() const OVERRIDE {
+    return false;
+  }
+  virtual void SetAudioMuted(bool muted) OVERRIDE {
+  }
+  virtual float GetVolumeLevel() const OVERRIDE {
+    return 0.0;
+  }
+  virtual void SetVolumeLevel(float level) OVERRIDE {
+  }
+
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DummyVolumeControlDelegate);
+};
+
 }  // namespace
 
-typedef AshTestBase SystemTrayTest;
+class SystemTrayTest : public AshTestBase {
+ public:
+  SystemTrayTest() : AshTestBase() {}
+  virtual ~SystemTrayTest() {}
+
+  virtual void SetUp() OVERRIDE {
+    AshTestBase::SetUp();
+    Shell::GetInstance()->accelerator_controller()->SetVolumeControlDelegate(
+        scoped_ptr<ash::VolumeControlDelegate>(new
+            DummyVolumeControlDelegate).Pass());
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SystemTrayTest);
+};
+
 
 TEST_F(SystemTrayTest, SystemTrayDefaultView) {
   SystemTray* tray = GetSystemTray();