cc: Add command line switch to control resource usage for impl-side painting.

cc/resources/resource_pool.h

Index: cc/resources/resource_pool.h
diff --git a/cc/resources/resource_pool.h b/cc/resources/resource_pool.h
index f3ef9bb51d33e52f111b77d09a7419603f92ad57..0f751c2b25b792f780603d95a6335f802db68364 100644
--- a/cc/resources/resource_pool.h
+++ b/cc/resources/resource_pool.h
@@ -44,13 +44,18 @@ class CC_EXPORT ResourcePool {
 
   void SetMaxMemoryUsageBytes(size_t max_memory_usage_bytes);
 
+  void ReduceMemoryUsage();
+
  protected:
   ResourcePool(ResourceProvider* resource_provider);
 
+  void EvictOneResource();
+
  private:
   ResourceProvider* resource_provider_;
   size_t max_memory_usage_bytes_;
   size_t memory_usage_bytes_;
+  size_t acquired_memory_usage_bytes_;
 
   typedef std::list<Resource*> ResourceList;
   ResourceList resources_;