[subresource_filter] Display dev tools console message for subresource blocking

third_party/WebKit/Source/core/loader/SubresourceFilter.cpp

Index: third_party/WebKit/Source/core/loader/SubresourceFilter.cpp
diff --git a/third_party/WebKit/Source/core/loader/SubresourceFilter.cpp b/third_party/WebKit/Source/core/loader/SubresourceFilter.cpp
index bdfbdf10756a94ec33a0dce2aeb67cb83cc3a41a..ac415e8fe12338f1ec3ed27b9bf49eb2fab946c4 100644
--- a/third_party/WebKit/Source/core/loader/SubresourceFilter.cpp
+++ b/third_party/WebKit/Source/core/loader/SubresourceFilter.cpp
@@ -6,13 +6,32 @@
 
 #include <utility>
 
+#include "core/dom/Document.h"
 #include "core/dom/TaskRunnerHelper.h"
+#include "core/frame/LocalFrame.h"
+#include "core/inspector/ConsoleMessage.h"
 #include "platform/WebTaskRunner.h"
 #include "platform/weborigin/KURL.h"
+#include "platform/wtf/text/StringBuilder.h"
 #include "public/platform/WebTraceLocation.h"
 
 namespace blink {
 
+namespace {
+
+void emitErrorForDisallowedLoads(const String& url, Document& document) {

[Charlie Harrison, 2017/05/22 14:35:04]

Since this is semantically the URL, let's just make it a KURL input and call
GetString() inside the method.

[Charlie Harrison, 2017/05/22 14:35:04]

Oh also, I think Blink doesn't do camel case functions anymore since the big
rename.

[shivanisha, 2017/05/23 18:54:00]

Done

+  // TODO(shivanisha): Update the string when finalized.
+  String message = "Subresource filtering disallowed loading this resource, ";

[Charlie Harrison, 2017/05/22 14:35:04]

Just inline this in Append so we can use the StringView optimizations and not do
potentially double allocations.

[shivanisha, 2017/05/23 18:54:00]

Done

+  StringBuilder builder;
+  builder.Append(message);
+  builder.Append(url);
+  builder.Append(".");
+  document.AddConsoleMessage(ConsoleMessage::Create(
+      kJSMessageSource, kErrorMessageLevel, builder.ToString()));
+}
+
+}  // namespace
+
 // static
 SubresourceFilter* SubresourceFilter::Create(
     DocumentLoader* loader,
@@ -36,8 +55,9 @@ bool SubresourceFilter::AllowLoad(
   // Pair<url string, context> -> LoadPolicy.
   WebDocumentSubresourceFilter::LoadPolicy load_policy =
       subresource_filter_->GetLoadPolicy(resource_url, request_context);
+
   if (reporting_policy == SecurityViolationReportingPolicy::kReport)
-    ReportLoad(load_policy);
+    ReportLoad(resource_url, load_policy);
   return load_policy != WebDocumentSubresourceFilter::kDisallow;
 }
 
@@ -54,21 +74,26 @@ bool SubresourceFilter::AllowWebSocketConnection(const KURL& url) {
   DCHECK(task_runner->RunsTasksOnCurrentThread());
   task_runner->PostTask(BLINK_FROM_HERE,
                         WTF::Bind(&SubresourceFilter::ReportLoad,
-                                  WrapPersistent(this), load_policy));
+                                  WrapPersistent(this), url, load_policy));
   return load_policy != WebDocumentSubresourceFilter::kDisallow;
 }
 
 void SubresourceFilter::ReportLoad(
+    const KURL& resource_url,
     WebDocumentSubresourceFilter::LoadPolicy load_policy) {
+  Document* document = document_loader_->GetFrame()
+                           ? document_loader_->GetFrame()->GetDocument()
+                           : nullptr;
   switch (load_policy) {
     case WebDocumentSubresourceFilter::kAllow:
       break;
     case WebDocumentSubresourceFilter::kDisallow:
       subresource_filter_->ReportDisallowedLoad();
+      if (subresource_filter_->ShouldLogToConsole() && document) {

[Charlie Harrison, 2017/05/22 14:35:03]

nit: check |document| first in the conditional since it's a simple null check.

[shivanisha, 2017/05/23 18:54:00]

done

+        emitErrorForDisallowedLoads(resource_url.GetString(), *document);
+      }
     // fall through
     case WebDocumentSubresourceFilter::kWouldDisallow:
-      // TODO(csharrison): log console errors here based on
-      // subresource_filter_->ShouldLogToConsole().
       document_loader_->DidObserveLoadingBehavior(
           kWebLoadingBehaviorSubresourceFilterMatch);
       break;