gin: Make it possible to use gin array buffers when running on top of blink

This approach won't let use share an array buffer with blink, however,
it's good enough for a mojo js app.

For gin::Wrappable objects that want to interact with blink APIs, they
need to provide a custom converter to and from WebArrayBuffer(View)

BUG=none
R=abarth@chromium.org, dslomov@chromium.org, sky@chromium.org

Review URL: https://codereview.chromium.org/172133002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252190 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 44 insertions, 20 deletions

diff --git a/gin/array_buffer.cc b/gin/array_buffer.cc
index ee9f2a5..68237bc 100644
--- a/gin/array_buffer.cc
+++ b/gin/array_buffer.cc
@@ -2,17 +2,23 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "gin/array_buffer.h"
-
 #include <stdlib.h>
 
+#include "base/logging.h"
+#include "gin/array_buffer.h"
+#include "gin/per_isolate_data.h"
+
 namespace gin {
 
+namespace {
+
+gin::WrapperInfo g_array_buffer_wrapper_info = {gin::kEmbedderNativeGin};
+
+}  // namespace
+
 COMPILE_ASSERT(V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT == 2,
                array_buffers_must_have_two_internal_fields);
 
-static const int kBufferViewPrivateIndex = 0;
-
 // ArrayBufferAllocator -------------------------------------------------------
 
 void* ArrayBufferAllocator::Allocate(size_t length) {
@@ -72,6 +78,7 @@ class ArrayBuffer::Private : public base::RefCounted<ArrayBuffer::Private> {
 
   v8::Persistent<v8::ArrayBuffer> array_buffer_;
   scoped_refptr<Private> self_reference_;
+  v8::Isolate* isolate_;
   void* buffer_;
   size_t length_;
 };
@@ -79,28 +86,34 @@ class ArrayBuffer::Private : public base::RefCounted<ArrayBuffer::Private> {
 scoped_refptr<ArrayBuffer::Private> ArrayBuffer::Private::From(
     v8::Isolate* isolate, v8::Handle<v8::ArrayBuffer> array) {
   if (array->IsExternal()) {
+    CHECK_EQ(WrapperInfo::From(v8::Handle<v8::Object>::Cast(array)),
+             &g_array_buffer_wrapper_info)
+        << "Cannot mix blink and gin ArrayBuffers";
     return make_scoped_refptr(static_cast<Private*>(
-        array->GetAlignedPointerFromInternalField(kBufferViewPrivateIndex)));
+        array->GetAlignedPointerFromInternalField(kEncodedValueIndex)));
   }
   return make_scoped_refptr(new Private(isolate, array));
 }
 
 ArrayBuffer::Private::Private(v8::Isolate* isolate,
                               v8::Handle<v8::ArrayBuffer> array)
-    : array_buffer_(isolate, array) {
+    : array_buffer_(isolate, array), isolate_(isolate) {
   // Take ownership of the array buffer.
+  CHECK(!array->IsExternal());
   v8::ArrayBuffer::Contents contents = array->Externalize();
   buffer_ = contents.Data();
   length_ = contents.ByteLength();
 
-  array->SetAlignedPointerInInternalField(kBufferViewPrivateIndex, this);
+  array->SetAlignedPointerInInternalField(kWrapperInfoIndex,
+                                          &g_array_buffer_wrapper_info);
+  array->SetAlignedPointerInInternalField(kEncodedValueIndex, this);
 
   self_reference_ = this;  // Cleared in WeakCallback.
   array_buffer_.SetWeak(this, WeakCallback);
 }
 
 ArrayBuffer::Private::~Private() {
-  ArrayBufferAllocator::SharedInstance()->Free(buffer_, length_);
+  PerIsolateData::From(isolate_)->allocator()->Free(buffer_, length_);
 }
 
 void ArrayBuffer::Private::WeakCallback(
diff --git a/gin/isolate_holder.cc b/gin/isolate_holder.cc
index 411f26a..430a716 100644
--- a/gin/isolate_holder.cc
+++ b/gin/isolate_holder.cc
@@ -53,14 +53,21 @@ IsolateHolder::IsolateHolder()
   constraints.ConfigureDefaults(base::SysInfo::AmountOfPhysicalMemory(),
                                 base::SysInfo::NumberOfProcessors());
   v8::SetResourceConstraints(isolate_, &constraints);
-  Init();
+  Init(ArrayBufferAllocator::SharedInstance());
 }
 
 IsolateHolder::IsolateHolder(v8::Isolate* isolate)
     : isolate_owner_(false),
       isolate_(isolate) {
   EnsureV8Initialized(false);
-  Init();
+  Init(NULL);
+}
+
+IsolateHolder::IsolateHolder(v8::Isolate* isolate,
+                             v8::ArrayBuffer::Allocator* allocator)
+    : isolate_owner_(false), isolate_(isolate) {
+  EnsureV8Initialized(false);
+  Init(allocator);
 }
 
 IsolateHolder::~IsolateHolder() {
@@ -69,10 +76,10 @@ IsolateHolder::~IsolateHolder() {
     isolate_->Dispose();
 }
 
-void IsolateHolder::Init() {
+void IsolateHolder::Init(v8::ArrayBuffer::Allocator* allocator) {
   v8::Isolate::Scope isolate_scope(isolate_);
   v8::HandleScope handle_scope(isolate_);
-  isolate_data_.reset(new PerIsolateData(isolate_));
+  isolate_data_.reset(new PerIsolateData(isolate_, allocator));
 }
 
 }  // namespace gin
diff --git a/gin/per_isolate_data.cc b/gin/per_isolate_data.cc
index 6c2397b..7de9047 100644
--- a/gin/per_isolate_data.cc
+++ b/gin/per_isolate_data.cc
@@ -5,6 +5,7 @@
 #include "gin/per_isolate_data.h"
 #include "gin/public/gin_embedders.h"
 
+using v8::ArrayBuffer;
 using v8::Eternal;
 using v8::Isolate;
 using v8::Local;
@@ -14,8 +15,9 @@ using v8::ObjectTemplate;
 
 namespace gin {
 
-PerIsolateData::PerIsolateData(Isolate* isolate)
-    : isolate_(isolate)  {
+PerIsolateData::PerIsolateData(Isolate* isolate,
+                               ArrayBuffer::Allocator* allocator)
+    : isolate_(isolate), allocator_(allocator) {
   isolate_->SetData(kEmbedderNativeGin, this);
 }
 
diff --git a/gin/per_isolate_data.h b/gin/per_isolate_data.h
index ed93545..18c230b 100644
--- a/gin/per_isolate_data.h
+++ b/gin/per_isolate_data.h
@@ -18,7 +18,7 @@ namespace gin {
 // class stores all the Gin-related data that varies per isolate.
 class GIN_EXPORT PerIsolateData {
  public:
-  explicit PerIsolateData(v8::Isolate* isolate);
+  PerIsolateData(v8::Isolate* isolate, v8::ArrayBuffer::Allocator* allocator);
   ~PerIsolateData();
 
   static PerIsolateData* From(v8::Isolate* isolate);
@@ -39,6 +39,7 @@ class GIN_EXPORT PerIsolateData {
   v8::Local<v8::FunctionTemplate> GetFunctionTemplate(WrapperInfo* info);
 
   v8::Isolate* isolate() { return isolate_; }
+  v8::ArrayBuffer::Allocator* allocator() { return allocator_; }
 
  private:
   typedef std::map<
@@ -49,6 +50,7 @@ class GIN_EXPORT PerIsolateData {
   // PerIsolateData doesn't actually own |isolate_|. Instead, the isolate is
   // owned by the IsolateHolder, which also owns the PerIsolateData.
   v8::Isolate* isolate_;
+  v8::ArrayBuffer::Allocator* allocator_;
   ObjectTemplateMap object_templates_;
   FunctionTemplateMap function_templates_;
 
diff --git a/gin/public/isolate_holder.h b/gin/public/isolate_holder.h
index d68e4d5..67c2335 100644
--- a/gin/public/isolate_holder.h
+++ b/gin/public/isolate_holder.h
@@ -8,10 +8,7 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "gin/gin_export.h"
-
-namespace v8 {
-class Isolate;
-}
+#include "v8/include/v8.h"
 
 namespace gin {
 
@@ -30,6 +27,9 @@ class PerIsolateData;
 class GIN_EXPORT IsolateHolder {
  public:
   IsolateHolder();
+  IsolateHolder(v8::Isolate* isolate, v8::ArrayBuffer::Allocator* allocator);
+
+  // TODO(jochen): Remove.
   explicit IsolateHolder(v8::Isolate* isolate);
 
   ~IsolateHolder();
@@ -37,7 +37,7 @@ class GIN_EXPORT IsolateHolder {
   v8::Isolate* isolate() { return isolate_; }
 
  private:
-  void Init();
+  void Init(v8::ArrayBuffer::Allocator* allocator);
 
   bool isolate_owner_;
   v8::Isolate* isolate_;