Revert of Removing browser.Start() and instead starts the browser at the point of creation.

tools/telemetry/telemetry/core/browser.py

Index: tools/telemetry/telemetry/core/browser.py
diff --git a/tools/telemetry/telemetry/core/browser.py b/tools/telemetry/telemetry/core/browser.py
index dca7a06176cbddf9d2d4909e42a9d185f97ec2e3..2d290a9b79ecb662bac2f73420623270391d25f7 100644
--- a/tools/telemetry/telemetry/core/browser.py
+++ b/tools/telemetry/telemetry/core/browser.py
@@ -27,9 +27,7 @@
     with browser_to_create.Create() as browser:
       ... do all your operations on browser here
   """
-  def __init__(self, backend, platform_backend, archive_path,
-               append_to_existing_wpr, make_javascript_deterministic,
-               credentials_path):
+  def __init__(self, backend, platform_backend):
     assert platform_backend.platform != None
 
     self._browser_backend = backend
@@ -38,29 +36,10 @@
     self._local_server_controller = local_server.LocalServerController(backend)
     self._tabs = tab_list.TabList(backend.tab_list_backend)
     self.credentials = browser_credentials.BrowserCredentials()
-    self.credentials.credentials_path = credentials_path
     self._platform_backend.DidCreateBrowser(self, self._browser_backend)
 
-    self.SetReplayArchivePath(archive_path,
-                              append_to_existing_wpr,
-                              make_javascript_deterministic)
-
-    browser_options = self._browser_backend.browser_options
-    self.platform.FlushDnsCache()
-    if browser_options.clear_sytem_cache_for_browser_and_profile_on_start:
-      if self.platform.CanFlushIndividualFilesFromSystemCache():
-        self.platform.FlushSystemCacheForDirectory(
-            self._browser_backend.profile_directory)
-        self.platform.FlushSystemCacheForDirectory(
-            self._browser_backend.browser_directory)
-      else:
-        self.platform.FlushEntireSystemCache()
-
-    self._browser_backend.SetBrowser(self)
-    self._browser_backend.Start()
-    self._platform_backend.DidStartBrowser(self, self._browser_backend)
-
   def __enter__(self):
+    self.Start()
     return self
 
   def __exit__(self, *args):
@@ -251,6 +230,22 @@
     del result['ProcessCount']
     return result
 
+  def Start(self):
+    browser_options = self._browser_backend.browser_options
+    self.platform.FlushDnsCache()
+    if browser_options.clear_sytem_cache_for_browser_and_profile_on_start:
+      if self.platform.CanFlushIndividualFilesFromSystemCache():
+        self.platform.FlushSystemCacheForDirectory(
+            self._browser_backend.profile_directory)
+        self.platform.FlushSystemCacheForDirectory(
+            self._browser_backend.browser_directory)
+      else:
+        self.platform.FlushEntireSystemCache()
+
+    self._browser_backend.SetBrowser(self)
+    self._browser_backend.Start()
+    self._platform_backend.DidStartBrowser(self, self._browser_backend)
+
   def Close(self):
     """Closes this browser."""
     if self._browser_backend.IsBrowserRunning():