Kill PageSet.AddPage and its remaining usage

content/test/gpu/gpu_tests/context_lost.py

Index: content/test/gpu/gpu_tests/context_lost.py
diff --git a/content/test/gpu/gpu_tests/context_lost.py b/content/test/gpu/gpu_tests/context_lost.py
index 95836d4a845d2d2143d73efbbc20037aa2ae21c9..f009c85c0e962f676a80960a7dd1c5c99ca8ad5f 100644
--- a/content/test/gpu/gpu_tests/context_lost.py
+++ b/content/test/gpu/gpu_tests/context_lost.py
@@ -328,10 +328,11 @@ class ContextLost(benchmark_module.Benchmark):
       file_path=data_path,
       user_agent_type='desktop',
       serving_dirs=set(['']))
-    ps.AddPage(GPUProcessCrashesExactlyOnce(ps, ps.base_dir))
-    ps.AddPage(WebGLContextLostFromGPUProcessExitPage(ps, ps.base_dir))
-    ps.AddPage(WebGLContextLostFromLoseContextExtensionPage(ps, ps.base_dir))
-    ps.AddPage(WebGLContextLostFromQuantityPage(ps, ps.base_dir))
-    ps.AddPage(WebGLContextLostFromSelectElementPage(ps, ps.base_dir))
-    ps.AddPage(WebGLContextLostInHiddenTabPage(ps, ps.base_dir))
+    ps.AddUserStory(GPUProcessCrashesExactlyOnce(ps, ps.base_dir))
+    ps.AddUserStory(WebGLContextLostFromGPUProcessExitPage(ps, ps.base_dir))
+    ps.AddUserStory(
+        WebGLContextLostFromLoseContextExtensionPage(ps, ps.base_dir))
+    ps.AddUserStory(WebGLContextLostFromQuantityPage(ps, ps.base_dir))
+    ps.AddUserStory(WebGLContextLostFromSelectElementPage(ps, ps.base_dir))
+    ps.AddUserStory(WebGLContextLostInHiddenTabPage(ps, ps.base_dir))
     return ps