Do not give GPU memory to backgrounded compositors.

content/common/gpu/client/context_provider_command_buffer.cc

Index: content/common/gpu/client/context_provider_command_buffer.cc
diff --git a/content/common/gpu/client/context_provider_command_buffer.cc b/content/common/gpu/client/context_provider_command_buffer.cc
index e992236f78ca565c7f2702a74f3aa0db6a6e0051..59034e12071ae7b4405e4ebdf98d30ded496edb6 100644
--- a/content/common/gpu/client/context_provider_command_buffer.cc
+++ b/content/common/gpu/client/context_provider_command_buffer.cc
@@ -204,11 +204,7 @@ void ContextProviderCommandBuffer::OnMemoryAllocationChanged(
   if (memory_policy_changed_callback_.is_null())
     return;
 
-  bool discard_backbuffer_when_not_visible =
-      !allocation.have_backbuffer_when_not_visible;
-
-  memory_policy_changed_callback_.Run(
-      cc::ManagedMemoryPolicy(allocation), discard_backbuffer_when_not_visible);
+  memory_policy_changed_callback_.Run(cc::ManagedMemoryPolicy(allocation));
 }
 
 bool ContextProviderCommandBuffer::InitializeCapabilities() {