Clear ResourceFetcher::m_validatedURLs if too many entries are added

Source/core/fetch/ResourceFetcher.cpp

Index: Source/core/fetch/ResourceFetcher.cpp
diff --git a/Source/core/fetch/ResourceFetcher.cpp b/Source/core/fetch/ResourceFetcher.cpp
index 68f29110590e6be5b393177aaab507a390eda98f..4a39eb603a850d723a5ae45a5c3ece1a0737ff58 100644
--- a/Source/core/fetch/ResourceFetcher.cpp
+++ b/Source/core/fetch/ResourceFetcher.cpp
@@ -694,6 +694,9 @@ void ResourceFetcher::requestLoadStarted(Resource* resource, const FetchRequest&
             m_resourceTimingReportTimer.startOneShot(0, FROM_HERE);
     }
 
+    if (m_validatedURLs.size() >= 10000) {
+        m_validatedURLs.clear();

[kouhei (in TOK), 2014/11/14 08:37:51]

Can we have a ring buffer instead?

[hiroshige, 2014/11/14 09:02:05]

Done.

[kouhei (in TOK), 2014/11/14 09:15:57]

Sorry, I guess this is a better approach for now. I didn't notice
m_validatedURLs is a HashSet.

s/10000/kMaxValidatedURLsSize/ and add a comment that this is to prevent memory
bloat on m_validatedURLs.

[hiroshige, 2014/11/14 09:29:21]

Done in Patch Set 3.

+    }
     m_validatedURLs.add(request.resourceRequest().url());
 }