Moving some functions from browser to app. Adding function prototypes to app backend.

tools/telemetry/telemetry/core/backends/app_backend.py

Index: tools/telemetry/telemetry/core/backends/app_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/app_backend.py b/tools/telemetry/telemetry/core/backends/app_backend.py
index 815c2dc400a38bc08fdab8aec5cb0f3e97131ca9..64314ca902c29b21869752f8450c8edc16913f05 100644
--- a/tools/telemetry/telemetry/core/backends/app_backend.py
+++ b/tools/telemetry/telemetry/core/backends/app_backend.py
@@ -4,9 +4,13 @@
 
 
 class AppBackend(object):
-  def __init__(self):
+  def __init__(self, app_type):
     super(AppBackend, self).__init__()
     self._app = None
+    self._app_type = app_type
+
+  def __del__(self):
+    self.Close()
 
   def SetApp(self, app):
     self._app = app
@@ -14,3 +18,26 @@ class AppBackend(object):
   @property
   def app(self):
     return self._app
+
+  @property
+  def app_type(self):
+    return self._app_type
+
+  def Start(self):
+    NotImplementedError()
+
+  def Close(self):
+    NotImplementedError()
+
+  @property
+  def pid(self):
+    NotImplementedError()
+
+  def IsAppRunning(self):
+    NotImplementedError()
+
+  def GetStandardOutput(self):
+    NotImplementedError()
+
+  def GetStackTrace(self):
+    NotImplementedError()