Update touch selection to only modify one selection point at a time.

content/browser/renderer_host/input/input_router_impl.cc

Index: content/browser/renderer_host/input/input_router_impl.cc
diff --git a/content/browser/renderer_host/input/input_router_impl.cc b/content/browser/renderer_host/input/input_router_impl.cc
index 441f9384bb8745e05efd53d9e1e645aa94255124..1d69de1d8f4b4248ddfe9322eb2a3fbdeb4f89d4 100644
--- a/content/browser/renderer_host/input/input_router_impl.cc
+++ b/content/browser/renderer_host/input/input_router_impl.cc
@@ -68,7 +68,7 @@ InputRouterImpl::InputRouterImpl(IPC::Sender* sender,
       client_(client),
       ack_handler_(ack_handler),
       routing_id_(routing_id),
-      select_range_pending_(false),
+      select_message_pending_(false),
       move_caret_pending_(false),
       mouse_move_pending_(false),
       mouse_wheel_pending_(false),
@@ -83,7 +83,11 @@ InputRouterImpl::InputRouterImpl(IPC::Sender* sender,
   UpdateTouchAckTimeoutEnabled();
 }
 
-InputRouterImpl::~InputRouterImpl() {}
+InputRouterImpl::~InputRouterImpl() {
+  for (auto* message : pending_select_messages_) {

[jdduke (slow), 2014/10/27 15:22:13]

Woo, range for!

For now, let's stick with STLDeleteElements(&pending_select_messages_);

I'll see if we can get a ScopedDeque smart container in base (or just wait until
we get proper move support with standard containers... =/).

+    delete message;
+  }
+}
 
 void InputRouterImpl::Flush() {
   flush_requested_ = true;
@@ -95,7 +99,8 @@ bool InputRouterImpl::SendInput(scoped_ptr<IPC::Message> message) {
   switch (message->type()) {
     // Check for types that require an ACK.
     case InputMsg_SelectRange::ID:
-      return SendSelectRange(message.Pass());
+    case InputMsg_MoveRangeSelectionExtent::ID:
+      return SendSelectMessage(message.Pass());
     case InputMsg_MoveCaret::ID:
       return SendMoveCaret(message.Pass());
     case InputMsg_HandleInputEvent::ID:
@@ -267,8 +272,10 @@ bool InputRouterImpl::OnMessageReceived(const IPC::Message& message) {
   IPC_BEGIN_MESSAGE_MAP(InputRouterImpl, message)
     IPC_MESSAGE_HANDLER(InputHostMsg_HandleInputEvent_ACK, OnInputEventAck)
     IPC_MESSAGE_HANDLER(InputHostMsg_DidOverscroll, OnDidOverscroll)
-    IPC_MESSAGE_HANDLER(ViewHostMsg_MoveCaret_ACK, OnMsgMoveCaretAck)
-    IPC_MESSAGE_HANDLER(ViewHostMsg_SelectRange_ACK, OnSelectRangeAck)
+    IPC_MESSAGE_HANDLER(InputHostMsg_MoveCaret_ACK, OnMsgMoveCaretAck)
+    IPC_MESSAGE_HANDLER(InputHostMsg_SelectRange_ACK, OnSelectMessageAck)
+    IPC_MESSAGE_HANDLER(InputHostMsg_MoveRangeSelectionExtent_ACK,
+                        OnSelectMessageAck)
     IPC_MESSAGE_HANDLER(ViewHostMsg_HasTouchEventHandlers,
                         OnHasTouchEventHandlers)
     IPC_MESSAGE_HANDLER(InputHostMsg_SetTouchAction,
@@ -298,14 +305,25 @@ void InputRouterImpl::OnGestureEventAck(
   ack_handler_->OnGestureEventAck(event, ack_result);
 }
 
-bool InputRouterImpl::SendSelectRange(scoped_ptr<IPC::Message> message) {
-  DCHECK(message->type() == InputMsg_SelectRange::ID);
-  if (select_range_pending_) {
-    next_selection_range_ = message.Pass();
+bool InputRouterImpl::SendSelectMessage(
+    scoped_ptr<IPC::Message> message) {
+  DCHECK(message->type() == InputMsg_SelectRange::ID ||
+         message->type() == InputMsg_MoveRangeSelectionExtent::ID);
+
+  // TODO(jdduke): Factor out common logic between selection and caret-related
+  //               IPC messages.
+  if (select_message_pending_) {
+    if (!pending_select_messages_.empty() &&
+        pending_select_messages_.back()->type() == message->type()) {
+      delete pending_select_messages_.back();
+      pending_select_messages_.pop_back();
+    }
+
+    pending_select_messages_.push_back(message.release());
     return true;
   }
 
-  select_range_pending_ = true;
+  select_message_pending_ = true;
   return Send(message.release());
 }
 
@@ -487,10 +505,12 @@ void InputRouterImpl::OnMsgMoveCaretAck() {
     SendMoveCaret(next_move_caret_.Pass());
 }
 
-void InputRouterImpl::OnSelectRangeAck() {
-  select_range_pending_ = false;
-  if (next_selection_range_)
-    SendSelectRange(next_selection_range_.Pass());
+void InputRouterImpl::OnSelectMessageAck() {
+  select_message_pending_ = false;
+  if (!pending_select_messages_.empty()) {
+    SendSelectMessage(make_scoped_ptr(pending_select_messages_.front()));
+    pending_select_messages_.pop_front();

[jdduke (slow), 2014/10/27 15:22:13]

As a precaution, let's store |front()| in a local scoped_ptr, then
|pop_front()|, then forward the local scoped_ptr (this shouldn't be an issue in
practice currently, but we've had issues with re-entrancy in the past so best to
make sure it works now).

+  }
 }
 
 void InputRouterImpl::OnHasTouchEventHandlers(bool has_handlers) {
@@ -679,7 +699,7 @@ bool InputRouterImpl::HasPendingEvents() const {
          !key_queue_.empty() ||
          mouse_move_pending_ ||
          mouse_wheel_pending_ ||
-         select_range_pending_ ||
+         select_message_pending_ ||
          move_caret_pending_;
 }