Bubble scroll events from WebView guest to embedder.

content/renderer/browser_plugin/browser_plugin_manager.cc

Index: content/renderer/browser_plugin/browser_plugin_manager.cc
diff --git a/content/renderer/browser_plugin/browser_plugin_manager.cc b/content/renderer/browser_plugin/browser_plugin_manager.cc
index 9cde47387883186a2913d9e515aa6f08ed9694b3..587e8021b67f27b8aa32dbfa5786a320d2ebc647 100644
--- a/content/renderer/browser_plugin/browser_plugin_manager.cc
+++ b/content/renderer/browser_plugin/browser_plugin_manager.cc
@@ -3,7 +3,10 @@
 // found in the LICENSE file.
 
 #include "content/renderer/browser_plugin/browser_plugin_manager.h"
+
 #include "base/memory/scoped_ptr.h"
+#include "base/threading/thread.h"
+#include "cc/base/completion_event.h"
 #include "content/common/browser_plugin/browser_plugin_constants.h"
 #include "content/common/browser_plugin/browser_plugin_messages.h"
 #include "content/common/frame_messages.h"
@@ -11,9 +14,59 @@
 #include "content/renderer/browser_plugin/browser_plugin.h"
 #include "content/renderer/render_thread_impl.h"
 #include "ipc/ipc_message_macros.h"
+#include "ipc/ipc_sync_channel.h"
+#include "ipc/message_filter.h"
 
 namespace content {
 
+class GuestScrollCompletionFilter : public IPC::MessageFilter {
+ public:
+  explicit GuestScrollCompletionFilter(
+      scoped_refptr<base::SingleThreadTaskRunner> io_task_runner)
+      : io_task_runner_(io_task_runner),
+        guest_handled_scroll_event_(true),
+        scroll_completion_event_(nullptr) {}
+
+  // IPC::MessageFilter implementation.
+  bool OnMessageReceived(const IPC::Message& message) override {
+    DCHECK(io_task_runner_->BelongsToCurrentThread());
+    // If we see the as-yet-to-be determined ack from the browser,
+    // set |guest_handled_scroll_event_| and call
+    // scroll_completion_event_->Signal().
+    bool handled = true;
+    IPC_BEGIN_MESSAGE_MAP(GuestScrollCompletionFilter, message)
+      IPC_MESSAGE_HANDLER(BrowserPluginMsg_SignalScrollCompletionEvent,
+                          OnSignalScrollCompletionEvent)
+      IPC_MESSAGE_UNHANDLED(handled = false)
+    IPC_END_MESSAGE_MAP()
+    return handled;
+  }
+
+  void set_scroll_completion_event(
+      cc::CompletionEvent* scroll_completion_event) {
+    scroll_completion_event_ = scroll_completion_event;
+  }
+  bool guest_handled_scroll_event() const {
+    return guest_handled_scroll_event_;
+  }
+
+ private:
+  ~GuestScrollCompletionFilter() override {}
+
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+  bool guest_handled_scroll_event_;
+  cc::CompletionEvent* scroll_completion_event_;
+
+  void OnSignalScrollCompletionEvent(bool handled) {
+    DCHECK(io_task_runner_->BelongsToCurrentThread());
+    guest_handled_scroll_event_ = handled;
+    scroll_completion_event_->Signal();
+    scroll_completion_event_ = nullptr;
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(GuestScrollCompletionFilter);
+};
+
 // static
 BrowserPluginManager* BrowserPluginManager::Get() {
   if (!RenderThreadImpl::current())
@@ -27,6 +80,13 @@ BrowserPluginManager::BrowserPluginManager() {
 BrowserPluginManager::~BrowserPluginManager() {
 }
 
+void BrowserPluginManager::Init(
+    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
+    IPC::SyncChannel* channel) {
+  scroll_completion_filter_ = new GuestScrollCompletionFilter(io_task_runner);
+  channel->AddFilter(scroll_completion_filter_.get());
+}
+
 void BrowserPluginManager::AddBrowserPlugin(
     int browser_plugin_instance_id,
     BrowserPlugin* browser_plugin) {
@@ -113,6 +173,15 @@ bool BrowserPluginManager::Send(IPC::Message* msg) {
   return RenderThreadImpl::current()->Send(msg);
 }
 
+bool BrowserPluginManager::GetScrollHandledStatus() {
+  cc::CompletionEvent scroll_completion_event;
+
+  scroll_completion_filter_->set_scroll_completion_event(
+      &scroll_completion_event);
+  scroll_completion_event.Wait();
+  return scroll_completion_filter_->guest_handled_scroll_event();
+}
+
 void BrowserPluginManager::OnCompositorFrameSwappedPluginUnavailable(
     const IPC::Message& message) {
   BrowserPluginMsg_CompositorFrameSwapped::Param param;