Refactoring: Move some classes from content/child to platform

content/child/web_discardable_memory_impl.cc

Index: content/child/web_discardable_memory_impl.cc
diff --git a/content/child/web_discardable_memory_impl.cc b/content/child/web_discardable_memory_impl.cc
index a92083c937d15a70632f3b87194d0820d8e77ae7..b2cdd205d5ad36386f1eb43d1a46546df27588a6 100644
--- a/content/child/web_discardable_memory_impl.cc
+++ b/content/child/web_discardable_memory_impl.cc
@@ -8,7 +8,7 @@
 
 #include "base/memory/discardable_memory.h"
 #include "base/memory/discardable_memory_allocator.h"
-#include "content/child/web_process_memory_dump_impl.h"
+#include "third_party/WebKit/public/platform/WebProcessMemoryDump.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 
 namespace content {
@@ -39,8 +39,8 @@ blink::WebMemoryAllocatorDump*
 WebDiscardableMemoryImpl::createMemoryAllocatorDump(
     const blink::WebString& name,
     blink::WebProcessMemoryDump* wpmd) const {
-  return static_cast<content::WebProcessMemoryDumpImpl*>(wpmd)
-      ->CreateDiscardableMemoryAllocatorDump(name.utf8(), discardable_.get());
+  return wpmd->createDiscardableMemoryAllocatorDump(
+      name.utf8(), discardable_.get());
 }
 
 WebDiscardableMemoryImpl::WebDiscardableMemoryImpl(