CC/GPU: Add a soft limit to the compositor.

cc/resources/tile_priority.h

Index: cc/resources/tile_priority.h
diff --git a/cc/resources/tile_priority.h b/cc/resources/tile_priority.h
index 0052e40ddce8e86129a55432cde7a33c1068f0e4..ea7d18fd47c0407de198d1a41b51110002136fa7 100644
--- a/cc/resources/tile_priority.h
+++ b/cc/resources/tile_priority.h
@@ -137,14 +137,16 @@ class GlobalStateThatImpactsTilePriority {
  public:
   GlobalStateThatImpactsTilePriority()
       : memory_limit_policy(ALLOW_NOTHING),
-        memory_limit_in_bytes(0),
+        soft_memory_limit_in_bytes(0),
+        hard_memory_limit_in_bytes(0),
         unused_memory_limit_in_bytes(0),
         num_resources_limit(0),
         tree_priority(SAME_PRIORITY_FOR_BOTH_TREES) {}
 
   TileMemoryLimitPolicy memory_limit_policy;
 
-  size_t memory_limit_in_bytes;
+  size_t soft_memory_limit_in_bytes;
+  size_t hard_memory_limit_in_bytes;
   size_t unused_memory_limit_in_bytes;
   size_t num_resources_limit;
 
@@ -152,7 +154,8 @@ class GlobalStateThatImpactsTilePriority {
 
   bool operator==(const GlobalStateThatImpactsTilePriority& other) const {
     return memory_limit_policy == other.memory_limit_policy
-        && memory_limit_in_bytes == other.memory_limit_in_bytes
+        && soft_memory_limit_in_bytes == other.soft_memory_limit_in_bytes
+        && hard_memory_limit_in_bytes == other.hard_memory_limit_in_bytes
         && unused_memory_limit_in_bytes == other.unused_memory_limit_in_bytes
         && num_resources_limit == other.num_resources_limit
         && tree_priority == other.tree_priority;