[Telemetry] Migrate bitmap.py from bitmaptools.cc to numpy

content/test/gpu/gpu_tests/maps.py

Index: content/test/gpu/gpu_tests/maps.py
diff --git a/content/test/gpu/gpu_tests/maps.py b/content/test/gpu/gpu_tests/maps.py
index 27a741d9248b9bd820018be29ed77d6fb7121303..12b33366f7151a8ed221242df72106bea6916360 100644
--- a/content/test/gpu/gpu_tests/maps.py
+++ b/content/test/gpu/gpu_tests/maps.py
@@ -14,7 +14,6 @@ import cloud_storage_test_base
 import maps_expectations
 
 from telemetry import benchmark
-from telemetry.core import bitmap
 from telemetry.core import util
 from telemetry.page import page
 from telemetry.page import page_set
@@ -33,7 +32,7 @@ class _MapsValidator(cloud_storage_test_base.ValidatorBase):
     if not tab.screenshot_supported:
       raise page_test.Failure('Browser does not support screenshot capture')
     screenshot = tab.Screenshot(5)
-    if not screenshot:
+    if screenshot is None:
       raise page_test.Failure('Could not capture screenshot')
 
     dpr = tab.EvaluateJavaScript('window.devicePixelRatio')