[chrome_remote_control] Use monkey patching for stubs.

tools/chrome_remote_control/chrome_remote_control/desktop_browser_finder_unittest.py

Index: tools/chrome_remote_control/chrome_remote_control/desktop_browser_finder_unittest.py
diff --git a/tools/chrome_remote_control/chrome_remote_control/desktop_browser_finder_unittest.py b/tools/chrome_remote_control/chrome_remote_control/desktop_browser_finder_unittest.py
index c75ab02450beedef0aa7dfe6c87918474a7ed101..2ec9392853e1205ef4b693d04f2c3a805503ad8e 100644
--- a/tools/chrome_remote_control/chrome_remote_control/desktop_browser_finder_unittest.py
+++ b/tools/chrome_remote_control/chrome_remote_control/desktop_browser_finder_unittest.py
@@ -5,10 +5,7 @@ import unittest
 
 from chrome_remote_control import browser_options
 from chrome_remote_control import desktop_browser_finder
-from chrome_remote_control.system_stub import (
-  OSModuleStub,
-  SysModuleStub
-  )
+from chrome_remote_control import system_stub
 
 # This file verifies the logic for finding a browser instance on all platforms
 # at once. It does so by providing stubs for the OS/sys/subprocess primitives
@@ -16,29 +13,22 @@ from chrome_remote_control.system_stub import (
 # We prefer this approach to having to run the same test on every platform on
 # which we want this code to work.
 
-class StubSubprocess(object):
-  def __init__(self):
-    self.call_hook = None
-
-  def call(self, *args, **kwargs):
-    assert self.call_hook
-    return self.call_hook(*args, **kwargs)
-
 class FindTestBase(unittest.TestCase):
   def setUp(self):
     self._options = browser_options.BrowserOptions()
     self._options.chrome_root = '../../../'
-    self._sys_stub = SysModuleStub()
-    self._os_stub = OSModuleStub(self._sys_stub)
-    self._subprocess_stub = StubSubprocess()
+    self._stubs = system_stub.Override(desktop_browser_finder,
+                                       ['os', 'subprocess', 'sys'])
+
+  def tearDown(self):
+    self._stubs.Restore()
 
   @property
   def _files(self):
-    return self._os_stub.files
+    return self._stubs.os.path.files
 
   def DoFindAll(self):
-    return desktop_browser_finder.FindAllAvailableBrowsers(self._options,
-        self._os_stub, self._sys_stub, self._subprocess_stub)
+    return desktop_browser_finder.FindAllAvailableBrowsers(self._options)
 
   def DoFindAllTypes(self):
     browsers = self.DoFindAll()
@@ -50,7 +40,7 @@ def has_type(array, browser_type):
 class OSXFindTest(FindTestBase):
   def setUp(self):
     super(OSXFindTest, self).setUp()
-    self._sys_stub.platform = 'darwin'
+    self._stubs.sys.platform = 'darwin'
     self._files.append('/Applications/Google Chrome Canary.app/'
                        'Contents/MacOS/Google Chrome Canary')
     self._files.append('/Applications/Google Chrome.app/' +
@@ -77,7 +67,7 @@ class LinuxFindTest(FindTestBase):
   def setUp(self):
     super(LinuxFindTest, self).setUp()
 
-    self._sys_stub.platform = 'linux2'
+    self._stubs.sys.platform = 'linux2'
     self._files.append('/foo/chrome')
     self._files.append('../../../out/Release/chrome')
     self._files.append('../../../out/Debug/chrome')
@@ -90,7 +80,7 @@ class LinuxFindTest(FindTestBase):
       if this.has_google_chrome_on_path:
         return 0
       raise OSError('Not found')
-    self._subprocess_stub.call_hook = call_hook
+    self._stubs.subprocess.call = call_hook
 
   def testFindAllWithExact(self):
     types = self.DoFindAllTypes()
@@ -124,16 +114,16 @@ class WinFindTest(FindTestBase):
   def setUp(self):
     super(WinFindTest, self).setUp()
 
-    self._sys_stub.platform = 'win32'
-    self._os_stub.local_app_data = 'c:\\Users\\Someone\\AppData\\Local'
+    self._stubs.sys.platform = 'win32'
+    self._stubs.os.local_app_data = 'c:\\Users\\Someone\\AppData\\Local'
     self._files.append('c:\\tmp\\chrome.exe')
     self._files.append('..\\..\\..\\build\\Release\\chrome.exe')
     self._files.append('..\\..\\..\\build\\Debug\\chrome.exe')
     self._files.append('..\\..\\..\\build\\Release\\content_shell.exe')
     self._files.append('..\\..\\..\\build\\Debug\\content_shell.exe')
-    self._files.append(self._os_stub.local_app_data + '\\' +
+    self._files.append(self._stubs.os.local_app_data + '\\' +
                        'Google\\Chrome\\Application\\chrome.exe')
-    self._files.append(self._os_stub.local_app_data + '\\' +
+    self._files.append(self._stubs.os.local_app_data + '\\' +
                        'Google\\Chrome SxS\\Application\\chrome.exe')
 
   def testFindAllGivenDefaults(self):