Add data reduction proxy integration tests for video compression.

tools/chrome_proxy/integration_tests/chrome_proxy_pagesets/__init__.py

Index: tools/chrome_proxy/integration_tests/chrome_proxy_pagesets/__init__.py
diff --git a/tools/chrome_proxy/integration_tests/chrome_proxy_pagesets/__init__.py b/tools/chrome_proxy/integration_tests/chrome_proxy_pagesets/__init__.py
index 910392815e8f3507de471c5f45712f36b82b0c75..9f24d4d4af7cebf3a0b12b1e76ec198a02a4ceee 100644
--- a/tools/chrome_proxy/integration_tests/chrome_proxy_pagesets/__init__.py
+++ b/tools/chrome_proxy/integration_tests/chrome_proxy_pagesets/__init__.py
@@ -8,6 +8,7 @@ import sys
 
 from telemetry.core import discover
 from telemetry.page import page_set
+import video
 
 
 # Import all submodules' PageSet classes.
@@ -17,3 +18,10 @@ base_class = page_set.PageSet
 for cls in discover.DiscoverClasses(
     start_dir, top_level_dir, base_class).values():
   setattr(sys.modules[__name__], cls.__name__, cls)
+
+# DiscoverClasses makes the assumption that there is exactly one matching
+# class per file, however the following are declared in the same file.
+for cls in (video.VideoDirectPageSet,
+            video.VideoProxiedPageSet,
+            video.VideoComparePageSet):
+  setattr(sys.modules[__name__], cls.__name__, cls)