[Origin Trials] Install origin trial bindings on V8 context conditionally

third_party/WebKit/Source/core/testing/v8/WebCoreTestSupport.cpp

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 #include "core/testing/v8/WebCoreTestSupport.h"
 
+#include "bindings/core/v8/DOMWrapperWorld.h"
+#include "bindings/core/v8/V8Binding.h"
 #include "bindings/core/v8/V8Internals.h"
+#include "bindings/core/v8/V8WorkerInternals.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/frame/LocalFrame.h"
+#include "core/origin_trials/OriginTrialContext.h"
 #include "core/testing/InternalSettings.h"
 #include "core/testing/Internals.h"
 #include "core/testing/WorkerInternals.h"
 
 using namespace blink;
 
 namespace WebCoreTestSupport {
 
+namespace {
+blink::initializeOriginTrialsFunction s_originalInitializeOriginTrialsFunction = nullptr;
+}
+
 v8::Local<v8::Value> createInternalsObject(v8::Local<v8::Context> context)
 {
     ScriptState* scriptState = ScriptState::from(context);
     v8::Local<v8::Object> global = scriptState->context()->Global();
     ExecutionContext* executionContext = scriptState->getExecutionContext();
     if (executionContext->isDocument())
         return toV8(Internals::create(scriptState), global, scriptState->isolate());
     if (executionContext->isWorkerGlobalScope())
         return toV8(WorkerInternals::create(scriptState), global, scriptState->isolate());
     return v8::Local<v8::Value>();
 }
 
 void injectInternalsObject(v8::Local<v8::Context> context)
 {
+    if (!s_originalInitializeOriginTrialsFunction) {
+        s_originalInitializeOriginTrialsFunction = setInitializeOriginTrialsFunction(initializeOriginTrialsForTests);
+    }
+
     ScriptState* scriptState = ScriptState::from(context);
     ScriptState::Scope scope(scriptState);
     v8::Local<v8::Object> global = scriptState->context()->Global();
     v8::Local<v8::Value> internals = createInternalsObject(context);
     if (internals.IsEmpty())
         return;
+
     v8CallOrCrash(global->Set(scriptState->context(), v8AtomicString(scriptState->isolate(), Internals::internalsId), internals));
+
+    // If Origin Trials have been registered before the internals object was ready,
+    // then inject them into the context now
+    ExecutionContext* executionContext = toExecutionContext(context);
+    if (executionContext) {
+        OriginTrialContext* originTrialContext = OriginTrialContext::from(executionContext);
+        if (originTrialContext)
+            originTrialContext->initializePendingTrials();
+    }
+}
+
+void initializeOriginTrialsForTests(v8::Local<v8::Context> context, const blink::DOMWrapperWorld& world)

[haraken, 2016/05/27 00:01:42]

Hmm, this adds a couple of complexity.

Alternately, can you write tests in layout tests? You can add origin-trials
attributes to window.internals (see Internal.idl) and enable the attributes
using <meta> tags.

[iclelland, 2016/05/27 03:19:43]

That's what we do -- see LayoutTests/http/origin_trials/ . The trouble is that
the tokens are encountered *before* the internals object is instantiated (It's
created very late) and so there is nothing to attach the attributes to at the
time that we would normally attach them.

What I do instead here is to add one more initialization function to the chain,
and then call initializeOriginTrials() one more time to add any new attributes,
*after* window.internals is instantiated.

[haraken, 2016/05/27 22:25:17]

I'm not sure if it's too late. In common cases, a window object is created after
a <head> tag is closed, where all tokens should have already been encountered.

If you really want to test a case where a new token is encountered after that
happens, can you add a <meta> tag after a <head> tag is closed?

(Then we can remove initializeOriginTrialsForTests and simplify the logic to
register function pointers for initializeOriginTrials.)

[iclelland, 2016/05/30 15:39:28]

That's true, but it's not window that is a problem here -- it's
window.internals, which is injected some time after the window object is
created.
V8Internals is only included in testing binaries. Regardless of when we call
V8Internals::installOriginTrialsSampleAPI, we can't reference it in
Source/bindings/core/v8/V8Binding.cpp or
Source/bindings/modules/v8/V8BindingForModules.cpp. 

+{
+    DCHECK(!context.IsEmpty());
+    (*s_originalInitializeOriginTrialsFunction)(context, world);
+    ExecutionContext* executionContext = toExecutionContext(context);
+    if (!executionContext->isDocument() && !executionContext->isWorkerGlobalScope())
+        return;
+    OriginTrialContext* originTrialContext = OriginTrialContext::from(executionContext, OriginTrialContext::DontCreateIfNotExists);
+    if (!originTrialContext)
+        return;
+
+    context->Enter();
+    v8::Isolate* isolate = context->GetIsolate();
+    v8::Local<v8::Object> global = context->Global();
+    // TODO(iclelland): This is a placeholder for the real interface object,
+    // which we don't try to obtain at this time. (An assertion in the bindings
+    // generation code prevents it from actually being used.) It should be
+    // replaced with the actual interface if possible, in order to allow origin
+    // trials on static attributes. (crbug.com/614352)
+    v8::Local<v8::Function> interface = v8::Function::New(context, nullptr).ToLocalChecked();
+
+    v8::Local<v8::String> internalsName = v8::String::NewFromUtf8(isolate, "internals", v8::NewStringType::kNormal).ToLocalChecked();
+    v8::Local<v8::Value> v8Internals = global->Get(context, internalsName).ToLocalChecked();
+    if (v8Internals->IsObject()) {
+        v8::Local<v8::Object> internals = v8Internals->ToObject();
+        if (!originTrialContext->featureBindingsInstalled("Frobulate") && originTrialContext->isFeatureEnabled("Frobulate", nullptr)) {
+            if (executionContext->isDocument())
+                V8Internals::installOriginTrialsSampleAPI(isolate, world, internals, interface);
+            else if (executionContext->isWorkerGlobalScope())
+                V8WorkerInternals::installOriginTrialsSampleAPI(isolate, world, internals, interface);
+            originTrialContext->setFeatureBindingsInstalled("Frobulate");
+        }
+    }
+    context->Exit();
 }
 
 void resetInternalsObject(v8::Local<v8::Context> context)
 {
     // This can happen if JavaScript is disabled in the main frame.
     if (context.IsEmpty())
         return;
 
     ScriptState* scriptState = ScriptState::from(context);
     ScriptState::Scope scope(scriptState);
     Document* document = toDocument(scriptState->getExecutionContext());
     ASSERT(document);
     LocalFrame* frame = document->frame();
     // Should the document have been detached, the page is assumed being destroyed (=> no reset required.)
     if (!frame)
         return;
     Page* page = frame->page();
     ASSERT(page);
     Internals::resetToConsistentState(page);
     InternalSettings::from(*page)->resetToConsistentState();
 }
 
 } // namespace WebCoreTestSupport