Retry browser startup in desktop_browser_finder.

telemetry/telemetry/internal/backends/chrome/desktop_browser_finder.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """Finds desktop browsers that can be controlled by telemetry."""
 
 import logging
 import os
 import sys
 
 import dependency_manager  # pylint: disable=import-error
@@ skipping 42 matching lines @@
   def Create(self, finder_options):
     if self._flash_path and not os.path.exists(self._flash_path):
       logging.warning(
           'Could not find Flash at %s. Continuing without Flash.\n'
           'To run with Flash, check it out via http://go/read-src-internal',
           self._flash_path)
       self._flash_path = None
 
     self._InitPlatformIfNeeded()
 
-    browser_backend = desktop_browser_backend.DesktopBrowserBackend(
-        self._platform_backend,
-        finder_options.browser_options, self._local_executable,
-        self._flash_path, self._is_content_shell, self._browser_directory)
-    return browser.Browser(
-        browser_backend, self._platform_backend, self._credentials_path)
+    num_retries = 3
+    for x in range(0, num_retries):
+      returned_browser = None
+      try:
+        returned_browser = None
+
+        browser_backend = desktop_browser_backend.DesktopBrowserBackend(
+            self._platform_backend,
+            finder_options.browser_options, self._local_executable,
+            self._flash_path, self._is_content_shell, self._browser_directory)
+
+        returned_browser = browser.Browser(
+            browser_backend, self._platform_backend, self._credentials_path)
+
+        # Try fetching the zeroth tab. If this works, then the browser
+        # appears to be working.
+        _ = returned_browser.tabs[0]

[Ken Russell (switch to Gerrit), 2017/05/08 21:22:02]

The fetching of the zeroth tab is causing
DevToolsClientBackendTest.testGetUpdatedInspectableContexts to fail. Even if
this tab is fetched and then immediately closed, this test still fails.

I'm removing this part of the CL. It looks like it still detects whether the
browser came up successfully.

+
+        return returned_browser
+      except Exception:
+        logging.warning('Browser creation failed (attempt %d of %d), retrying' %
+                        ((x + 1), num_retries))
+        # Attempt to clean up things left over from the failed browser startup.
+        try:
+          if returned_browser:
+            returned_browser.Close()
+        except Exception:
+          pass
+        # Re-raise the exception the last time through.
+        if x == num_retries - 1:
+          raise
 
   def SupportsOptions(self, browser_options):
     if ((len(browser_options.extensions_to_load) != 0)
         and self._is_content_shell):
       return False
     return True
 
   def UpdateExecutableIfNeeded(self):
     pass
 
@@ skipping 200 matching lines @@
     if "--ozone-platform" in arg:
       has_ozone_platform = True
 
   if len(browsers) and not has_x11_display and not has_ozone_platform:
     logging.warning(
       'Found (%s), but you do not have a DISPLAY environment set.' %
       ','.join([b.browser_type for b in browsers]))
     return []
 
   return browsers