Added test to ensure context restoration due to GC doesn't crash (Take 2)

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 0acab358ee00628994ed35df12ba30b461d58e25..633df6022bc1c19eb7ba24a77f5a1f9e2f211968 100644
--- a/content/test/gpu/gpu_tests/context_lost.py
+++ b/content/test/gpu/gpu_tests/context_lost.py
@@ -102,6 +102,27 @@ class _ContextLostValidator(page_test.PageTest):
           'window.domAutomationController._succeeded'):
           raise page_test.Failure(
             'Test failed (context not restored properly?)')
+    elif page.force_garbage_collection:
+      # Try to corce GC to clean up any contexts not attached to the page.
+      # This method seem unreliable, so the page will also attempt to force
+      # GC through excessive allocations.
+      tab.CollectGarbage()
+      completed = False
+      try:
+        print "Waiting for page to finish."
+        util.WaitFor(lambda: tab.EvaluateJavaScript(
+            'window.domAutomationController._finished'), wait_timeout)
+        completed = True
+      except util.TimeoutException:
+        pass
+
+      if not completed:
+        raise page_test.Failure(
+            'Test didn\'t complete (no context restored event?)')
+      if not tab.EvaluateJavaScript(
+        'window.domAutomationController._succeeded'):
+        raise page_test.Failure(
+          'Test failed (context not restored properly?)')
 
 class WebGLContextLostFromGPUProcessExitPage(page.Page):
   def __init__(self, page_set, base_dir):
@@ -113,6 +134,7 @@ class WebGLContextLostFromGPUProcessExitPage(page.Page):
     self.script_to_evaluate_on_commit = harness_script
     self.kill_gpu_process = True
     self.number_of_gpu_process_kills = 1
+    self.force_garbage_collection = False
 
   def RunNavigateSteps(self, action_runner):
     action_runner.RunAction(NavigateAction())
@@ -129,12 +151,28 @@ class WebGLContextLostFromLoseContextExtensionPage(page.Page):
     self.name = 'ContextLost.WebGLContextLostFromLoseContextExtension',
     self.script_to_evaluate_on_commit = harness_script
     self.kill_gpu_process = False
+    self.force_garbage_collection = False
 
   def RunNavigateSteps(self, action_runner):
     action_runner.RunAction(NavigateAction())
     action_runner.RunAction(WaitAction(
       {'javascript': 'window.domAutomationController._finished'}))
 
+class WebGLContextLostFromQuantityPage(page.Page):
+  def __init__(self, page_set, base_dir):
+    super(WebGLContextLostFromQuantityPage, self).__init__(
+      url='file://webgl.html?query=forced_quantity_loss',
+      page_set=page_set,
+      base_dir=base_dir)
+    self.name = 'ContextLost.WebGLContextLostFromQuantity',
+    self.script_to_evaluate_on_commit = harness_script
+    self.kill_gpu_process = False
+    self.force_garbage_collection = True
+
+  def RunNavigateSteps(self, action_runner):
+    action_runner.RunAction(NavigateAction())
+    action_runner.RunAction(WaitAction(
+      {'javascript': 'window.domAutomationController._loaded'}))
 
 class ContextLost(test_module.Test):
   enabled = True
@@ -150,4 +188,7 @@ class ContextLost(test_module.Test):
       serving_dirs=set(['']))
     ps.AddPage(WebGLContextLostFromGPUProcessExitPage(ps, ps.base_dir))
     ps.AddPage(WebGLContextLostFromLoseContextExtensionPage(ps, ps.base_dir))
+    ps.AddPage(WebGLContextLostFromQuantityPage(ps, ps.base_dir))
     return ps
+
+