[Telemetry] Implement automatic installation of optional openCV dependecy.

tools/telemetry/telemetry/core/platform/linux_platform_backend_unittest.py

Index: tools/telemetry/telemetry/core/platform/linux_platform_backend_unittest.py
diff --git a/tools/telemetry/telemetry/core/platform/linux_platform_backend_unittest.py b/tools/telemetry/telemetry/core/platform/linux_platform_backend_unittest.py
index bc7465f7d1854ffca59bcf6e6473397f65d4921c..12e59b5d14be09be96cca3c3a8d6d900c164f5e2 100644
--- a/tools/telemetry/telemetry/core/platform/linux_platform_backend_unittest.py
+++ b/tools/telemetry/telemetry/core/platform/linux_platform_backend_unittest.py
@@ -6,6 +6,7 @@ import os
 import unittest
 
 from telemetry import decorators
+from telemetry.core import platform
 from telemetry.core import util
 from telemetry.core.platform import linux_platform_backend
 
@@ -70,3 +71,15 @@ class LinuxPlatformBackendTest(unittest.TestCase):
     # a distribution may not have a codename or a release number. We just check
     # that GetOSVersionName doesn't raise an exception
     backend.GetOSVersionName()
+
+  @decorators.Enabled('linux')
+  def testOpenCVDependency(self):
+    try:
+      import cv2
+      if (cv2.__version__ != '2.4.10'):
+        raise ImportError()
+    except ImportError:
+      platform.GetHostPlatform().InstallPythonModule('cv2')
+      import cv2
+    self.assertEqual('2.4.10', cv2.__version__, 'Wrong OpenCV version found. '
+      'Expected 2.4.10, but newer versions may be okay.')