[Telemetry] Factor out common logic between inspector backend lists.

tools/telemetry/telemetry/core/backends/chrome/tab_list_backend.py

Index: tools/telemetry/telemetry/core/backends/chrome/tab_list_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend.py b/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend.py
index cdc5cb3a69a53dd8d642c53a5fc82608cbfc1559..a0af16cac028cde64ad08da8edf61415ce221ee7 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend.py
@@ -2,44 +2,36 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import json
 import urllib2
 
 from telemetry.core import tab
 from telemetry.core import util
-from telemetry.core.backends.chrome import inspector_backend
+from telemetry.core.backends.chrome import inspector_backend_list
 
 
-class TabListBackend(object):
-  def __init__(self, browser_backend):
-    self._browser_backend = browser_backend
-
-    # Stores web socket debugger URLs in iteration order.
-    self._tab_list = []
-    # Maps debugger URLs to Tab objects.
-    self._tab_dict = {}
+class TabListBackend(inspector_backend_list.InspectorBackendList):
+  """A dynamic sequence of tab.Tabs in UI order."""
 
-  def Init(self):
-    self._UpdateTabList()
+  def __init__(self, browser_backend):
+    super(TabListBackend, self).__init__(browser_backend,
+                                         backend_wrapper=tab.Tab)
 
   def New(self, timeout):
     assert self._browser_backend.supports_tab_control
-
     self._browser_backend.Request('new', timeout=timeout)
-    return self.Get(-1, None, timeout=timeout)
+    return self[-1]
 
   def DoesDebuggerUrlExist(self, debugger_url):
-    return self._FindTabInfo(debugger_url) is not None
+    tab_id = inspector_backend_list.DebuggerUrlToId(debugger_url)
+    return bool(self[tab_id])
 
   def CloseTab(self, debugger_url, timeout=None):
     assert self._browser_backend.supports_tab_control
-
+    tab_id = inspector_backend_list.DebuggerUrlToId(debugger_url)
     # TODO(dtu): crbug.com/160946, allow closing the last tab on some platforms.
     # For now, just create a new tab before closing the last tab.
     if len(self) <= 1:
       self.New(timeout)
-
-    tab_id = debugger_url.split('/')[-1]
     try:
       response = self._browser_backend.Request('close/%s' % tab_id,
                                                timeout=timeout,
@@ -47,18 +39,12 @@ class TabListBackend(object):
     except urllib2.HTTPError:
       raise Exception('Unable to close tab, tab id not found: %s' % tab_id)
     assert response == 'Target is closing'
-
-    util.WaitFor(lambda: not self._FindTabInfo(debugger_url), timeout=5)
-
-    if debugger_url in self._tab_dict:
-      del self._tab_dict[debugger_url]
-    self._UpdateTabList()
+    util.WaitFor(lambda: tab_id not in self, timeout=5)
 
   def ActivateTab(self, debugger_url, timeout=None):
     assert self._browser_backend.supports_tab_control
-
-    assert debugger_url in self._tab_dict
-    tab_id = debugger_url.split('/')[-1]
+    tab_id = inspector_backend_list.DebuggerUrlToId(debugger_url)
+    assert tab_id in self
     try:
       response = self._browser_backend.Request('activate/%s' % tab_id,
                                                timeout=timeout,
@@ -68,69 +54,20 @@ class TabListBackend(object):
     assert response == 'Target activated'
 
   def GetTabUrl(self, debugger_url):
-    tab_info = self._FindTabInfo(debugger_url)
+    tab_id = inspector_backend_list.DebuggerUrlToId(debugger_url)
+    tab_info = self.GetContextInfo(tab_id)
     assert tab_info is not None
     return tab_info['url']
 
-  def __iter__(self):
-    self._UpdateTabList()
-    return self._tab_list.__iter__()
-
-  def __len__(self):
-    self._UpdateTabList()
-    return len(self._tab_list)
-
-  def Get(self, index, ret, timeout=60):
-    """Returns self[index] if it exists, or ret if index is out of bounds.
-    """
-    self._UpdateTabList()
-    if len(self._tab_list) <= index:
+  def Get(self, index, ret):
+    """Returns self[index] if it exists, or ret if index is out of bounds."""
+    if len(self) <= index:
       return ret
-    debugger_url = self._tab_list[index]
-    # Lazily get/create a Tab object.
-    tab_object = self._tab_dict.get(debugger_url)
-    if not tab_object:
-      backend = inspector_backend.InspectorBackend(
-          self._browser_backend.browser,
-          self._browser_backend,
-          debugger_url,
-          timeout=timeout)
-      tab_object = tab.Tab(backend)
-      self._tab_dict[debugger_url] = tab_object
-    return tab_object
-
-  def __getitem__(self, index):
-    tab_object = self.Get(index, None)
-    if tab_object is None:
-      raise IndexError('list index out of range')
-    return tab_object
-
-  def _ListTabs(self, timeout=None):
-    def _IsTab(context):
-      if 'type' in context:
-        return context['type'] == 'page'
-      # TODO: For compatibility with Chrome before r177683.
-      # This check is not completely correct, see crbug.com/190592.
-      return not context['url'].startswith('chrome-extension://')
-    data = self._browser_backend.Request('', timeout=timeout)
-    all_contexts = json.loads(data)
-    tabs = filter(_IsTab, all_contexts)
-    return tabs
-
-  def _UpdateTabList(self):
-    def GetDebuggerUrl(tab_info):
-      if 'webSocketDebuggerUrl' not in tab_info:
-        return None
-      return tab_info['webSocketDebuggerUrl']
-    new_tab_list = map(GetDebuggerUrl, self._ListTabs())
-    self._tab_list = [t for t in self._tab_list
-                      if t in self._tab_dict or t in new_tab_list]
-    self._tab_list += [t for t in new_tab_list
-                       if t is not None and t not in self._tab_list]
-
-  def _FindTabInfo(self, debugger_url):
-    tab_id = debugger_url.split('/')[-1]
-    for tab_info in self._ListTabs():
-      if tab_info.get('id') == tab_id:
-        return tab_info
-    return None
+    return self[index]
+
+  def ShouldIncludeContext(self, context):
+    if 'type' in context:
+      return context['type'] == 'page'
+    # TODO: For compatibility with Chrome before r177683.
+    # This check is not completely correct, see crbug.com/190592.
+    return not context['url'].startswith('chrome-extension://')