Revert of Refactoring: Move some classes from content/child to platform

third_party/WebKit/public/platform/Platform.h

Index: third_party/WebKit/public/platform/Platform.h
diff --git a/third_party/WebKit/public/platform/Platform.h b/third_party/WebKit/public/platform/Platform.h
index 72a3e189e3049825a6a3621c558bfaab13f5455d..a706079bce4738ef2c57b5a8b4a50fb97ffa0e99 100644
--- a/third_party/WebKit/public/platform/Platform.h
+++ b/third_party/WebKit/public/platform/Platform.h
@@ -424,10 +424,10 @@ public:
     // registerMemoryDumpProvider() method. |name| is used for debugging
     // (duplicates are allowed) and must be a long-lived C string.
     // See crbug.com/458295 for design docs.
-    BLINK_PLATFORM_EXPORT virtual void registerMemoryDumpProvider(blink::WebMemoryDumpProvider*, const char* name);
+    virtual void registerMemoryDumpProvider(blink::WebMemoryDumpProvider*, const char* name) { }
 
     // Must be called on the thread that called registerMemoryDumpProvider().
-    BLINK_PLATFORM_EXPORT virtual void unregisterMemoryDumpProvider(blink::WebMemoryDumpProvider*);
+    virtual void unregisterMemoryDumpProvider(blink::WebMemoryDumpProvider*) { }
 
     class TraceLogEnabledStateObserver {
     public:
@@ -440,6 +440,9 @@ public:
     virtual void addTraceLogEnabledStateObserver(TraceLogEnabledStateObserver*) {}
     virtual void removeTraceLogEnabledStateObserver(TraceLogEnabledStateObserver*) {}
 
+    // Returns a newly allocated WebProcessMemoryDump instance.
+    virtual blink::WebProcessMemoryDump* createProcessMemoryDump() { return nullptr; }
+
     typedef uint64_t WebMemoryAllocatorDumpGuid;
 
     // Returns guid corresponding to the given string (the hash value) for