Refactored bisect results dicts into a separate class

tools/auto_bisect/bisect_perf_regression_test.py

Index: tools/auto_bisect/bisect_perf_regression_test.py
diff --git a/tools/auto_bisect/bisect_perf_regression_test.py b/tools/auto_bisect/bisect_perf_regression_test.py
index d25992d18adf04272348130d85d096b1b2374aa0..2c1d9a2b9e9ebc9749c43f83f770bc7e839e15fa 100644
--- a/tools/auto_bisect/bisect_perf_regression_test.py
+++ b/tools/auto_bisect/bisect_perf_regression_test.py
@@ -32,6 +32,12 @@ def _GetBisectPerformanceMetricsInstance():
 class BisectPerfRegressionTest(unittest.TestCase):
   """Test case for other functions and classes in bisect-perf-regression.py."""
 
+  def setUp(self):
+    self.cwd = os.getcwd()
+
+  def tearDown(self):
+    os.chdir(self.cwd)
+
   def _AssertConfidence(self, score, bad_values, good_values):
     """Checks whether the given sets of values have a given confidence score.
 
@@ -282,7 +288,7 @@ class BisectPerfRegressionTest(unittest.TestCase):
 
   def testUpdateDepsContent(self):
     bisect_instance = _GetBisectPerformanceMetricsInstance()
-    deps_file = 'DEPS'
+    deps_file = os.path.join(bisect_perf_regression.SRC_DIR, 'DEPS')
     # We are intentionally reading DEPS file contents instead of string literal
     # with few lines from DEPS because to check if the format we are expecting
     # to search is not changed in DEPS content.