Adding test to ensure context restoration due to GC doesn't crash

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 f80a78e632f1994eb9ee44c7682e77d62f07e30c..bd76460183dca7255f0e2baf9ed4fca5d283aa8a 100644
--- a/content/test/gpu/gpu_tests/context_lost.py
+++ b/content/test/gpu/gpu_tests/context_lost.py
@@ -91,6 +91,26 @@ class _ContextLostValidator(page_test.PageTest):
           raise page_test.Failure(
             'Test failed (context not restored properly?)')
 
+    elif page.force_garbage_collection:
+      # Force GC to clean up any contexts not attached to the page.
+      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 ContextLost(test_module.Test):
   enabled = True
   test = _ContextLostValidator
@@ -114,6 +134,7 @@ class ContextLost(test_module.Test):
           ],
           'kill_gpu_process': True,
           'number_of_gpu_process_kills': 1,
+          'force_garbage_collection': False
         },
         {
           'name': 'ContextLost.WebGLContextLostFromLoseContextExtension',
@@ -124,7 +145,20 @@ class ContextLost(test_module.Test):
             { 'action': 'wait',
               'javascript': 'window.domAutomationController._finished' }
           ],
-          'kill_gpu_process': False
+          'kill_gpu_process': False,
+          'force_garbage_collection': False
+        },
+        {
+          'name': 'ContextLost.WebGLContextLostFromQuantity',
+          'url': 'file://webgl.html?query=forced_quantity_loss',
+          'script_to_evaluate_on_commit': harness_script,
+          'navigate_steps': [
+            { 'action': 'navigate' },
+            { 'action': 'wait',
+              'javascript': 'window.domAutomationController._loaded' }
+          ],
+          'kill_gpu_process': False,
+          'force_garbage_collection': True
         },
       ]
     }