PPAPI: Support sending browser-hosted resources synchronously

content/renderer/pepper/resource_converter.cc

Index: content/renderer/pepper/resource_converter.cc
diff --git a/content/renderer/pepper/resource_converter.cc b/content/renderer/pepper/resource_converter.cc
index 2af3bba3e7799d5864281bc05397c88e052477e3..6094e8a04073d2bcceb2c4a3c1a212d299cb8ae6 100644
--- a/content/renderer/pepper/resource_converter.cc
+++ b/content/renderer/pepper/resource_converter.cc
@@ -5,11 +5,12 @@
 #include "content/renderer/pepper/resource_converter.h"
 
 #include "base/bind.h"
+#include "base/callback.h"
 #include "base/message_loop/message_loop.h"
-#include "content/public/renderer/renderer_ppapi_host.h"
 #include "content/renderer/pepper/pepper_file_system_host.h"
 #include "content/renderer/pepper/pepper_media_stream_audio_track_host.h"
 #include "content/renderer/pepper/pepper_media_stream_video_track_host.h"
+#include "content/renderer/pepper/renderer_ppapi_host_impl.h"
 #include "ipc/ipc_message.h"
 #include "ppapi/host/ppapi_host.h"
 #include "ppapi/host/resource_host.h"
@@ -29,17 +30,6 @@ using ppapi::ResourceVar;
 namespace content {
 namespace {
 
-void FlushComplete(
-    const base::Callback<void(bool)>& callback,
-    const std::vector<scoped_refptr<content::HostResourceVar> >& browser_vars,
-    const std::vector<int>& pending_host_ids) {
-  CHECK(browser_vars.size() == pending_host_ids.size());
-  for (size_t i = 0; i < browser_vars.size(); ++i) {
-    browser_vars[i]->set_pending_browser_host_id(pending_host_ids[i]);
-  }
-  callback.Run(true);
-}
-
 // Converts a blink::WebFileSystem::Type to a PP_FileSystemType.
 PP_FileSystemType WebFileSystemTypeToPPAPI(blink::WebFileSystem::Type type) {
   switch (type) {
@@ -198,7 +188,8 @@ bool DOMMediaStreamTrackToResource(
 ResourceConverter::~ResourceConverter() {}
 
 ResourceConverterImpl::ResourceConverterImpl(PP_Instance instance)
-    : instance_(instance) {}
+    : instance_(instance),
+      weak_ptr_factory_(this) {}
 
 ResourceConverterImpl::~ResourceConverterImpl() {
   // Verify Flush() was called.
@@ -276,12 +267,36 @@ bool ResourceConverterImpl::NeedsFlush() {
 }
 
 void ResourceConverterImpl::Flush(const base::Callback<void(bool)>& callback) {
-  RendererPpapiHost::GetForPPInstance(instance_)->CreateBrowserResourceHosts(
-      instance_,
-      browser_host_create_messages_,
-      base::Bind(&FlushComplete, callback, browser_vars_));
+  pending_conversions_.push(PendingConversion());
+  pending_conversions_.back().callback = callback;
+  pending_conversions_.back().browser_vars.swap(browser_vars_);
+  pending_conversions_.back().sequence_num =
+      RendererPpapiHost::GetForPPInstance(instance_)->
+          CreateBrowserResourceHosts(
+              instance_,
+              browser_host_create_messages_,
+              base::Bind(&ResourceConverterImpl::FlushComplete,
+                         weak_ptr_factory_.GetWeakPtr()));
+
   browser_host_create_messages_.clear();
-  browser_vars_.clear();
+}
+
+void ResourceConverterImpl::FlushSync() {
+  // Send a request to the browser. We depend here on the fact that the async
+  // message generated by Flush will arrive before our synchronous request for
+  // all pending hosts.
+  //
+  // We don't need a response for this, since we'll get the result back in the
+  // response to calling GetAllPendingBrowserHosts, so use a null callback.
+  base::Callback<void(bool)> null_callback;
+  Flush(null_callback);
+
+  std::vector<ppapi::proxy::CompletedBrowserResourceHosts> completed_hosts;
+  RendererPpapiHostImpl* host_impl = static_cast<RendererPpapiHostImpl*>(
+      RendererPpapiHost::GetForPPInstance(instance_));
+  host_impl->GetAllPendingBrowserHosts(instance_, &completed_hosts);
+  for (const auto& completed_host_set : completed_hosts)
+    FlushComplete(completed_host_set);
 }
 
 bool ResourceConverterImpl::ToV8Value(const PP_Var& var,
@@ -332,6 +347,9 @@ bool ResourceConverterImpl::ToV8Value(const PP_Var& var,
   }
 }
 
+ResourceConverterImpl::PendingConversion::PendingConversion() {}
+ResourceConverterImpl::PendingConversion::~PendingConversion() {}
+
 scoped_refptr<HostResourceVar> ResourceConverterImpl::CreateResourceVar(
     int pending_renderer_id,
     const IPC::Message& create_message) {
@@ -350,4 +368,22 @@ ResourceConverterImpl::CreateResourceVarWithBrowserHost(
   return result;
 }
 
+void ResourceConverterImpl::FlushComplete(
+    const ppapi::proxy::CompletedBrowserResourceHosts& hosts) {
+  if (pending_conversions_.empty() ||
+      hosts.sequence_id < pending_conversions_.front().sequence_num) {
+    // We must have already processed this result, so we can ignore it.
+    return;
+  }
+  const PendingConversion& conversion = pending_conversions_.front();
+  CHECK(conversion.browser_vars.size() == hosts.host_ids.size());
+  for (size_t i = 0; i < conversion.browser_vars.size(); ++i) {
+    conversion.browser_vars[i]->set_pending_browser_host_id(
+        hosts.host_ids[i]);
+  }
+  if (!conversion.callback.is_null())
+    conversion.callback.Run(true);
+  pending_conversions_.pop();
+}
+
 }  // namespace content