Respect the order of input messages from browser to renderer

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index cbbbb089b03b3d37be90c0b1caf83db005d2196d..5699b20575819ec5778d840047291185cb77cdac 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -96,6 +96,7 @@
 #include "content/renderer/history_serialization.h"
 #include "content/renderer/image_downloader/image_downloader_impl.h"
 #include "content/renderer/ime_event_guard.h"
+#include "content/renderer/input/input_handler_manager.h"
 #include "content/renderer/internal_document_state_data.h"
 #include "content/renderer/manifest/manifest_manager.h"
 #include "content/renderer/media/audio_device_factory.h"
@@ -1221,6 +1222,17 @@ void RenderFrameImpl::Initialize() {
   // We delay calling this until we have the WebFrame so that any observer or
   // embedder can call GetWebFrame on any RenderFrame.
   GetContentClient()->renderer()->RenderFrameCreated(this);
+
+  // TODO(changwan): apply this logic to RenderWidget once we add input handler

[no sievers, 2016/06/01 22:14:47]

nit: i'd remove this TODO here since IIUC you intend to leave the code here as
is

[Changwan Ryu, 2016/06/03 06:48:29]

Removed.

+  // in RenderWidget, too.
+  if (render_view_ && render_view_->HasAddedInputHandler()) {

[no sievers, 2016/06/01 22:14:47]

This looks fragile. Do you expect HasAddedInputHandler() to be always true?
It just seems like call sequences could change somewhere, and your change would
silently become nonfunctional.

[Changwan Ryu, 2016/06/02 10:49:06]

Two hidden assumptions here:
1) initializeLayerTreeView() is part of RenderViewImpl::Initialize().
2) RenderViewImpl::Initialize() is created before RenderFrameImpl::Initialize().

I think as long as those two are met, RegisterRoutingID() should be called. I am
not sure if those assumptions are easily breakable.

But there is a chance that this fix can break in the future because there is no
rigorous test around it. I'll try a bit more but I found it challenging to add a
test that instantiates a real RenderThreadImpl object and test it against
RenderViewImpl / RenderFrameImpl / RenderWidget while pausing and resuming the
impl thread.

[Changwan Ryu, 2016/06/03 06:48:29]

Removed render_view check and changed to DCHECK(). Let me know if there is more
to do to.

+    RenderThreadImpl* render_thread = RenderThreadImpl::current();
+    // render_thread may be NULL in tests.
+    InputHandlerManager* input_handler_manager =
+        render_thread ? render_thread->input_handler_manager() : nullptr;
+    if (input_handler_manager)
+      input_handler_manager->RegisterRoutingID(GetRoutingID());

[no sievers, 2016/06/01 22:14:47]

How does it get unregistered?

[Changwan Ryu, 2016/06/03 06:48:29]

Now it's unregistered in ~RenderFrameImpl().

+  }
 }
 
 void RenderFrameImpl::InitializeBlameContext(RenderFrameImpl* parent_frame) {
@@ -1512,6 +1524,8 @@ bool RenderFrameImpl::OnMessageReceived(const IPC::Message& msg) {
                         OnExtendSelectionAndDelete)
     IPC_MESSAGE_HANDLER(InputMsg_SetCompositionFromExistingText,
                         OnSetCompositionFromExistingText)
+    IPC_MESSAGE_HANDLER(InputMsg_SetEditableSelectionOffsets,
+                        OnSetEditableSelectionOffsets)
     IPC_MESSAGE_HANDLER(InputMsg_ExecuteNoValueEditCommand,
                         OnExecuteNoValueEditCommand)
     IPC_MESSAGE_HANDLER(FrameMsg_CSSInsertRequest, OnCSSInsertRequest)
@@ -1524,8 +1538,6 @@ bool RenderFrameImpl::OnMessageReceived(const IPC::Message& msg) {
                         OnJavaScriptExecuteRequestInIsolatedWorld)
     IPC_MESSAGE_HANDLER(FrameMsg_VisualStateRequest,
                         OnVisualStateRequest)
-    IPC_MESSAGE_HANDLER(FrameMsg_SetEditableSelectionOffsets,
-                        OnSetEditableSelectionOffsets)
     IPC_MESSAGE_HANDLER(FrameMsg_Reload, OnReload)
     IPC_MESSAGE_HANDLER(FrameMsg_ReloadLoFiImages, OnReloadLoFiImages)
     IPC_MESSAGE_HANDLER(FrameMsg_TextSurroundingSelectionRequest,