[Telemetry] Make sure that browser.tabs.__iter__() return the tab object instead of tab's context_id

BUG=473202
CQ_EXTRA_TRYBOTS=tryserver.chromium.perf:linux_perf_bisect;tryserver.chromium.perf:mac_perf_bisect;tryserver.chromium.perf:android_nexus5_perf_bisect

Review URL: https://codereview.chromium.org/1197473002

Cr-Commit-Position: refs/heads/master@{#335643}

5 files changed, 13 insertions, 11 deletions

diff --git a/tools/perf/measurements/tab_switching.py b/tools/perf/measurements/tab_switching.py
index d4110e1..22d9370 100644
--- a/tools/perf/measurements/tab_switching.py
+++ b/tools/perf/measurements/tab_switching.py
@@ -81,8 +81,7 @@ class TabSwitching(page_test.PageTest):
         histogram_type, histogram_name, tab)
     prev_histogram = first_histogram
 
-    for i in xrange(len(tab.browser.tabs)):
-      t = tab.browser.tabs[i]
+    for t in tab.browser.tabs:
       t.Activate()
       def _IsDone():
         cur_histogram = histogram_util.GetHistogram(
diff --git a/tools/telemetry/telemetry/core/backends/chrome/extension_backend.py b/tools/telemetry/telemetry/core/backends/chrome/extension_backend.py
index aba475d..f0f4e7e 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/extension_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/extension_backend.py
@@ -28,7 +28,7 @@ class ExtensionBackendDict(collections.Mapping):
 
   def __getitem__(self, extension_id):
     extensions = []
-    for context_id in self._extension_backend_list:
+    for context_id in self._extension_backend_list.IterContextIds():
       if self.ContextIdToExtensionId(context_id) == extension_id:
         extensions.append(
             self._extension_backend_list.GetBackendFromContextId(context_id))
@@ -37,8 +37,8 @@ class ExtensionBackendDict(collections.Mapping):
     return extensions
 
   def __iter__(self):
-    for context_id in self._extension_backend_list:
-      yield self.ContextIdToExtensionId(context_id)
+    for context_id in self._extension_backend_list.IterContextIds():
+      yield self._extension_backend_list.GetBackendFromContextId(context_id)
 
   def __len__(self):
     return len(self._extension_backend_list)
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 e63bacc..bd89946 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend.py
@@ -48,7 +48,7 @@ class TabListBackend(inspector_backend_list.InspectorBackendList):
     if response != 'Target is closing':
       raise TabUnexpectedResponseException('Received response: %s' % response)
 
-    util.WaitFor(lambda: tab_id not in self, timeout=5)
+    util.WaitFor(lambda: tab_id not in self.IterContextIds(), timeout=5)
 
   def ActivateTab(self, tab_id, timeout=30):
     """Activates the tab with the given debugger_url.
diff --git a/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py b/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py
index c5a81c4..98a2dc8 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py
@@ -16,7 +16,7 @@ class TabListBackendTest(tab_test_case.TabTestCase):
 
     # Check that the tab.id matches context_id.
     tabs = []
-    for context_id in self.tabs:
+    for context_id in self.tabs._tab_list_backend.IterContextIds():
       tab = self.tabs.GetTabById(context_id)
       self.assertEquals(tab.id, context_id)
       tabs.append(self.tabs.GetTabById(context_id))
@@ -27,9 +27,7 @@ class TabListBackendTest(tab_test_case.TabTestCase):
     while len(self.tabs) < 2:
       self.tabs.New()
 
-    tabs = []
-    for context_id in self.tabs:
-      tabs.append(self.tabs.GetTabById(context_id))
+    tabs = [t for t in self.tabs]
 
     # Crash the first tab.
     self.assertRaises(exceptions.DevtoolsTargetCrashException,
diff --git a/tools/telemetry/telemetry/core/backends/chrome_inspector/inspector_backend_list.py b/tools/telemetry/telemetry/core/backends/chrome_inspector/inspector_backend_list.py
index 3521866..7e1f8fb 100644
--- a/tools/telemetry/telemetry/core/backends/chrome_inspector/inspector_backend_list.py
+++ b/tools/telemetry/telemetry/core/backends/chrome_inspector/inspector_backend_list.py
@@ -82,10 +82,15 @@ class InspectorBackendList(collections.Sequence):
       self._wrapper_dict[context_id] = wrapper
     return self._wrapper_dict[context_id]
 
-  def __iter__(self):
+  def IterContextIds(self):
     self._Update()
     return iter(self._filtered_context_ids)
 
+  def __iter__(self):
+    self._Update()
+    for context_id in self._filtered_context_ids:
+      yield self.GetTabById(context_id)
+
   def __len__(self):
     self._Update()
     return len(self._filtered_context_ids)