Throttle SelectRange IPC

This code is used by the Android port. We add a SelectRange_ACK to
throttle the rate at which the selection changes. Without throttling,
the selection handle updates can fall behind the user's touch input.

BUG=138939


Review URL: https://chromiumcodereview.appspot.com/10823077

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@151304 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/render_widget_host_impl.cc

@@ -130,6 +130,7 @@ RenderWidgetHostImpl::RenderWidgetHostImpl(RenderWidgetHostDelegate* delegate,
       should_auto_resize_(false),
       mouse_move_pending_(false),
       mouse_wheel_pending_(false),
+      select_range_pending_(false),
       needs_repainting_on_restore_(false),
       is_unresponsive_(false),
       in_flight_event_count_(0),
@@ -285,6 +286,7 @@ bool RenderWidgetHostImpl::OnMessageReceived(const IPC::Message &msg) {
     IPC_MESSAGE_HANDLER(ViewHostMsg_UpdateIsDelayed, OnMsgUpdateIsDelayed)
     IPC_MESSAGE_HANDLER(ViewHostMsg_HandleInputEvent_ACK, OnMsgInputEventAck)
     IPC_MESSAGE_HANDLER(ViewHostMsg_BeginSmoothScroll, OnMsgBeginSmoothScroll)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_SelectRange_ACK, OnMsgSelectRangeAck)
     IPC_MESSAGE_HANDLER(ViewHostMsg_Focus, OnMsgFocus)
     IPC_MESSAGE_HANDLER(ViewHostMsg_Blur, OnMsgBlur)
     IPC_MESSAGE_HANDLER(ViewHostMsg_HasTouchEventHandlers,
@@ -1083,6 +1085,10 @@ void RenderWidgetHostImpl::RendererExited(base::TerminationStatus status,
   mouse_wheel_pending_ = false;
   coalesced_mouse_wheel_events_.clear();
 
+  // Must reset these to ensure that SelectRange works with a new renderer.
+  select_range_pending_ = false;
+  next_selection_range_.reset();
+
   // Must reset these to ensure that gesture events work with a new renderer.
   gesture_event_filter_->Reset();
 
@@ -1586,6 +1592,14 @@ void RenderWidgetHostImpl::TickActiveSmoothScrollGesture() {
   }
 }
 
+void RenderWidgetHostImpl::OnMsgSelectRangeAck() {
+  select_range_pending_ = false;
+  if (next_selection_range_.get()) {
+    scoped_ptr<SelectionRange> next(next_selection_range_.Pass());
+    SelectRange(next->start, next->end);
+  }
+}
+
 void RenderWidgetHostImpl::ProcessWheelAck(bool processed) {
   mouse_wheel_pending_ = false;
 
@@ -1878,6 +1892,16 @@ void RenderWidgetHostImpl::ScrollFocusedEditableNodeIntoRect(
 
 void RenderWidgetHostImpl::SelectRange(const gfx::Point& start,
                                        const gfx::Point& end) {
+  if (select_range_pending_) {
+    if (!next_selection_range_.get()) {
+      next_selection_range_.reset(new SelectionRange());
+    }
+    next_selection_range_->start = start;
+    next_selection_range_->end = end;
+    return;
+  }
+
+  select_range_pending_ = true;
   Send(new ViewMsg_SelectRange(GetRoutingID(), start, end));
 }
 

content/browser/renderer_host/render_widget_host_impl.h

@@ -505,6 +505,7 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   void OnMsgInputEventAck(WebKit::WebInputEvent::Type event_type,
                           bool processed);
   void OnMsgBeginSmoothScroll(bool scroll_down, bool scroll_far);
+  void OnMsgSelectRangeAck();
   virtual void OnMsgFocus();
   virtual void OnMsgBlur();
   void OnMsgHasTouchEventHandlers(bool has_handlers);
@@ -681,6 +682,15 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   // would be queued) results in very slow scrolling.
   WheelEventQueue coalesced_mouse_wheel_events_;
 
+  // (Similar to |mouse_move_pending_|.) True while waiting for SelectRange_ACK.
+  bool select_range_pending_;
+
+  // (Similar to |next_mouse_move_|.) The next SelectRange to send, if any.
+  struct SelectionRange {
+    gfx::Point start, end;
+  };
+  scoped_ptr<SelectionRange> next_selection_range_;
+
   // The time when an input event was sent to the RenderWidget.
   base::TimeTicks input_event_start_time_;
 

content/common/view_messages.h

@@ -978,6 +978,7 @@ IPC_MESSAGE_ROUTED0(ViewMsg_SelectAll)
 IPC_MESSAGE_ROUTED0(ViewMsg_Unselect)
 
 // Requests the renderer to select the region between two points.
+// Expects a SelectRange_ACK message when finished.
 IPC_MESSAGE_ROUTED2(ViewMsg_SelectRange,
                     gfx::Point /* start */,
                     gfx::Point /* end */)
@@ -1841,6 +1842,8 @@ IPC_MESSAGE_ROUTED2(ViewHostMsg_SetTooltipText,
                     string16 /* tooltip text string */,
                     WebKit::WebTextDirection /* text direction hint */)
 
+IPC_MESSAGE_ROUTED0(ViewHostMsg_SelectRange_ACK)
+
 // Notification that the text selection has changed.
 // Note: The secound parameter is the character based offset of the string16
 // text in the document.

content/renderer/render_view_impl.cc

@@ -1297,6 +1297,8 @@ void RenderViewImpl::OnSelectRange(const gfx::Point& start,
   if (!webview())
     return;
 
+  Send(new ViewHostMsg_SelectRange_ACK(routing_id_));
+
   handling_select_range_ = true;
   webview()->focusedFrame()->selectRange(start, end);
   handling_select_range_ = false;