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

third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp b/third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp
index 44f8a1e7a85e2a92ee440459aa221eefaba9befa..dbaef4d0324e7214a22c640f2a8bc1277a07c65c 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp
@@ -818,6 +818,33 @@ v8::Local<v8::Context> toV8ContextEvenIfDetached(Frame* frame, DOMWrapperWorld&
     return frame->windowProxy(world)->contextIfInitialized();
 }
 
+void initializeOriginTrialsCore(v8::Local<v8::Context> context, const DOMWrapperWorld& world)

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

Who calls this method? I guess initializeOriginTrialsForModules need to call
initializeOriginTrialsCore?

Another option would be to follow the same pattern as
toExecutionContextForModules. You can register a function pointer of
initializeOriginTrialsForModules and make initializeOriginTrialsCore call
initializeOriginTrialsForModules. (I'd prefer this.)

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

Yes, when registerInitializeOriginTrialsForModules changes the
s_initializeOriginTrials function pointer, it receives a pointer to this
function, which it stores, and then calls as its first action.
I originally wrote it that way here (mimicking that pattern).

The problem, (besides getting the core/modules dependency backwards) is that it
was difficult to imagine a good way to extend it, and I need to extend it for
tests.

If this file stores a "forModules" pointer, and V8BindingForModules doesn't
store anything, and I want the code that manages the internals object to insert
its own initialization function into the chain, then I'd need to break the
layering even further: Either *core* needs to also call an initializeForTests
pointer, or *modules* needs to have an initializeForTests pointer, when neither
of them should, in general, even be aware of tests. 

+{
+    // TODO(iclelland): Generate all of this logic at compile-time, based on the
+    // configuration of origin trial enabled attibutes and interfaces in IDL
+    // files. (crbug.com/615060)
+
+    DCHECK(!context.IsEmpty());
+    // Initialization code for origin trials for core bindings, if necessary,
+    // should go here.
+}
+
+namespace {
+initializeOriginTrialsFunction s_initializeOriginTrialsFunction = &initializeOriginTrialsCore;
+}
+
+void initializeOriginTrials(v8::Local<v8::Context> context, const DOMWrapperWorld& world)
+{
+    (*s_initializeOriginTrialsFunction)(context, world);
+}
+
+initializeOriginTrialsFunction setInitializeOriginTrialsFunction(initializeOriginTrialsFunction newInitializeOriginTrialsFunction)
+{
+    initializeOriginTrialsFunction originalFunction = s_initializeOriginTrialsFunction;
+    s_initializeOriginTrialsFunction = newInitializeOriginTrialsFunction;
+    return originalFunction;
+}
+
 void crashIfIsolateIsDead(v8::Isolate* isolate)
 {
     if (isolate->IsDead()) {