Convert received V8 values before forwarding to the PDF plugin

Implement PostMessageReceiver::PostMessage() to convert a v8::Value
received from the embedding content to a base::Value prior to forwarding
it to the PDF plugin.

Bug: 1109796
Change-Id: Ibf6697d693db656897f791e2cbd082fcc413cce1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2601241
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: K. Moon <kmoon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#848685}

pdf/BUILD.gn

@@ -283,6 +283,7 @@ if (enable_pdf) {
       ":ppapi_migration",
       "//base",
       "//cc/paint",
+      "//content/public/renderer",
       "//gin",
       "//ppapi/cpp:objects",  # TODO(crbug.com/1114263): PDFEngine::Client only.
       "//third_party/blink/public:blink_headers",

pdf/DEPS

@@ -1,5 +1,6 @@
 include_rules = [
   "+cc/paint",
+  "+content/public/renderer/v8_value_converter.h",
   "+gin/handle.h",
   "+gin/public",
   "+gin/object_template_builder.h",

pdf/post_message_receiver.cc

@@ -4,6 +4,7 @@
 
 #include "pdf/post_message_receiver.h"
 
+#include <memory>
 #include <utility>
 
 #include "base/bind.h"
@@ -12,6 +13,7 @@
 #include "base/notreached.h"
 #include "base/sequenced_task_runner.h"
 #include "base/values.h"
+#include "content/public/renderer/v8_value_converter.h"
 #include "gin/handle.h"
 #include "gin/object_template_builder.h"
 #include "gin/public/wrapper_info.h"
@@ -29,7 +31,7 @@ v8::Local<v8::Object> PostMessageReceiver::Create(
     base::WeakPtr<Client> client,
     scoped_refptr<base::SequencedTaskRunner> client_task_runner) {
   return gin::CreateHandle(
-             isolate, new PostMessageReceiver(std::move(client),
+             isolate, new PostMessageReceiver(isolate, std::move(client),
                                               std::move(client_task_runner)))
       .ToV8()
       .As<v8::Object>();
@@ -38,9 +40,11 @@ v8::Local<v8::Object> PostMessageReceiver::Create(
 PostMessageReceiver::~PostMessageReceiver() = default;
 
 PostMessageReceiver::PostMessageReceiver(
+    v8::Isolate* isolate,
     base::WeakPtr<Client> client,
     scoped_refptr<base::SequencedTaskRunner> client_task_runner)
-    : client_(std::move(client)),
+    : isolate_(isolate),
+      client_(std::move(client)),
       client_task_runner_(std::move(client_task_runner)) {}
 
 gin::ObjectTemplateBuilder PostMessageReceiver::GetObjectTemplateBuilder(
@@ -53,14 +57,29 @@ const char* PostMessageReceiver::GetTypeName() {
   return "ChromePdfPostMessageReceiver";
 }
 
+std::unique_ptr<base::Value> PostMessageReceiver::ConvertMessage(
+    v8::Local<v8::Value> message) {
+  if (!v8_value_converter_)
+    v8_value_converter_ = content::V8ValueConverter::Create();
+
+  return v8_value_converter_->FromV8Value(message,
+                                          isolate_->GetCurrentContext());
+}
+
 void PostMessageReceiver::PostMessage(v8::Local<v8::Value> message) {
   if (!client_)
     return;
 
-  NOTIMPLEMENTED_LOG_ONCE();
+  std::unique_ptr<base::Value> converted_message = ConvertMessage(message);
+  if (!converted_message) {
+    NOTREACHED() << "The PDF Viewer UI should not be sending messages that "
+                    "cannot be converted.";
+    return;
+  }
 
-  client_task_runner_->PostTask(
+  client_task_runner_->PostTask(FROM_HERE,
-      FROM_HERE, base::BindOnce(&Client::OnMessage, client_, base::Value()));
+                                base::BindOnce(&Client::OnMessage, client_,
+                                               std::move(*converted_message)));
 }
 
 }  // namespace chrome_pdf

pdf/post_message_receiver.h

@@ -5,6 +5,8 @@
 #ifndef PDF_POST_MESSAGE_RECEIVER_H_
 #define PDF_POST_MESSAGE_RECEIVER_H_
 
+#include <memory>
+
 #include "base/memory/scoped_refptr.h"
 #include "base/memory/weak_ptr.h"
 #include "gin/public/wrapper_info.h"
@@ -16,6 +18,10 @@ class SequencedTaskRunner;
 class Value;
 }  // namespace base
 
+namespace content {
+class V8ValueConverter;
+}  // namespace content
+
 namespace gin {
 class ObjectTemplateBuilder;
 }  // namespace gin
@@ -57,6 +63,7 @@ class PostMessageReceiver final : public gin::Wrappable<PostMessageReceiver> {
 
  private:
   PostMessageReceiver(
+      v8::Isolate* isolate,
       base::WeakPtr<Client> client,
       scoped_refptr<base::SequencedTaskRunner> client_task_runner);
 
@@ -65,9 +72,16 @@ class PostMessageReceiver final : public gin::Wrappable<PostMessageReceiver> {
       v8::Isolate* isolate) override;
   const char* GetTypeName() override;
 
+  // Converts `message` so it can be consumed by `client_`.
+  std::unique_ptr<base::Value> ConvertMessage(v8::Local<v8::Value> message);
+
   // Implements the `postMessage()` method called by the embedder.
   void PostMessage(v8::Local<v8::Value> message);
 
+  std::unique_ptr<content::V8ValueConverter> v8_value_converter_;
+
+  v8::Isolate* isolate_;
+
   base::WeakPtr<Client> client_;
 
   scoped_refptr<base::SequencedTaskRunner> client_task_runner_;