[Telemetry] Implement automatic installation of optional openCV dependecy.

tools/telemetry/telemetry/core/platform/linux_platform_backend.py

Index: tools/telemetry/telemetry/core/platform/linux_platform_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/linux_platform_backend.py b/tools/telemetry/telemetry/core/platform/linux_platform_backend.py
index 54fde65707b7e81da791bab67dc4d8b1a485da6b..a61d93a1b06dc03ce40930356484d88d00465a26 100644
--- a/tools/telemetry/telemetry/core/platform/linux_platform_backend.py
+++ b/tools/telemetry/telemetry/core/platform/linux_platform_backend.py
@@ -96,6 +96,13 @@ class LinuxPlatformBackend(
       raise NotImplementedError(
           'Please teach Telemetry how to install ' + application)
 
+  def InstallPythonModule(self, module):
+    if module == 'cv2':
+      self._InstallOpenCV()
+    else:
+      raise NotImplementedError(
+          'Please teach Telemetry how to install python module ' + module)
+
   def CanMonitorPower(self):
     return self._power_monitor.CanMonitorPower()
 
@@ -154,6 +161,12 @@ class LinuxPlatformBackend(
         'You may proceed by manually building and installing dummynet for ' \
         'your kernel. See: http://info.iet.unipi.it/~luigi/dummynet/'
 
+  def _InstallOpenCV(self):
+    # This package is installed by install-build-deps.sh, so bots should never
+    # reach this. Only those running the standalone telemetry library should
+    # hit this, unless there's a bug.
+    subprocess.check_call(['sudo', 'apt-get', '-q', 'install', 'python-opencv'])
+
   def _InstallBinary(self, bin_name, fallback_package=None):
     bin_path = support_binaries.FindPath(
         bin_name, self.GetArchName(), self.GetOSName())