Do not calculate composition bounds until IME requests.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 129ed07f6eb454e478f97327fc3e4969ea84065a..9caa17202b6138eb6f370ba4673fcbed5138c8a1 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -252,6 +252,7 @@ RenderWidget::RenderWidget(CompositorDependencies* compositor_deps,
       device_scale_factor_(screen_info_.deviceScaleFactor),
 #if defined(OS_ANDROID)
       text_field_is_dirty_(false),
+      monitor_composition_info_(false),
 #endif
       popup_origin_scale_for_emulation_(0.f),
       frame_swap_message_queue_(new FrameSwapMessageQueue()),
@@ -497,6 +498,7 @@ bool RenderWidget::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(InputMsg_ImeEventAck, OnImeEventAck)
     IPC_MESSAGE_HANDLER(InputMsg_RequestTextInputStateUpdate,
                         OnRequestTextInputStateUpdate)
+    IPC_MESSAGE_HANDLER(InputMsg_RequestCursorUpdate, OnRequestCursorUpdate)
     IPC_MESSAGE_HANDLER(ViewMsg_ShowImeIfNeeded, OnShowImeIfNeeded)
 #endif
     IPC_MESSAGE_HANDLER(ViewMsg_HandleCompositorProto, OnHandleCompositorProto)
@@ -1371,7 +1373,8 @@ void RenderWidget::OnImeSetComposition(
     // sure we are in a consistent state.
     Send(new InputHostMsg_ImeCancelComposition(routing_id()));
   }
-  UpdateCompositionInfo(true);
+  UpdateCompositionInfo(true /* update composition range */,
+                        false /* force update */);
 }
 
 void RenderWidget::OnImeConfirmComposition(const base::string16& text,
@@ -1388,7 +1391,8 @@ void RenderWidget::OnImeConfirmComposition(const base::string16& text,
   else
     webwidget_->confirmComposition(WebWidget::DoNotKeepSelection);
   input_handler_->set_handling_input_event(false);
-  UpdateCompositionInfo(true);
+  UpdateCompositionInfo(true /* update composition range */,
+                        false /* force update */);
 }
 
 void RenderWidget::OnDeviceScaleFactorChanged() {
@@ -1469,7 +1473,12 @@ ui::TextInputType RenderWidget::GetTextInputType() {
   return ui::TEXT_INPUT_TYPE_NONE;
 }
 
-void RenderWidget::UpdateCompositionInfo(bool should_update_range) {
+void RenderWidget::UpdateCompositionInfo(
+        bool should_update_range, bool force_update) {
+#if defined(OS_ANDROID)
+  if (!monitor_composition_info_)
+    return;  // Do not calculate composition info if not requested.
+#endif  // OS_ANDROID
   TRACE_EVENT0("renderer", "RenderWidget::UpdateCompositionInfo");
   gfx::Range range = gfx::Range();
   if (should_update_range) {
@@ -1480,7 +1489,7 @@ void RenderWidget::UpdateCompositionInfo(bool should_update_range) {
   std::vector<gfx::Rect> character_bounds;
   GetCompositionCharacterBounds(&character_bounds);
 
-  if (!ShouldUpdateCompositionInfo(range, character_bounds))
+  if (!force_update && !ShouldUpdateCompositionInfo(range, character_bounds))
     return;
   composition_character_bounds_ = character_bounds;
   composition_range_ = range;
@@ -1538,6 +1547,15 @@ void RenderWidget::OnRequestTextInputStateUpdate() {
   UpdateSelectionBounds();
   UpdateTextInputState(ShowIme::HIDE_IME, ChangeSource::FROM_IME);
 }
+
+void RenderWidget::OnRequestCursorUpdate(
+    bool immediate_request, bool monitor_request) {
+  monitor_composition_info_ = monitor_request;
+  if (!immediate_request)
+    return;
+  UpdateCompositionInfo(true /* update composition range */,
+                        true /* force update */);
+}
 #endif
 
 bool RenderWidget::ShouldHandleImeEvent() {
@@ -1718,7 +1736,8 @@ void RenderWidget::UpdateSelectionBounds() {
     }
   }
 
-  UpdateCompositionInfo(false);
+  UpdateCompositionInfo(false /* update composition range */,
+                        false /* force update */);
 }
 
 void RenderWidget::SetDeviceColorProfileForTesting(
@@ -1818,7 +1837,8 @@ void RenderWidget::resetInputMethod() {
       Send(new InputHostMsg_ImeCancelComposition(routing_id()));
   }
 
-  UpdateCompositionInfo(true);
+  UpdateCompositionInfo(true /* update composition range */,
+                        false /* force update */);
 }
 
 #if defined(OS_ANDROID)