Do not calculate composition bounds until IME requests.

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index c91e0b83841cce5d3acffe130c73d5a7c27ae08c..daee7170916a6f19d73599d623067aec40007639 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -352,7 +352,9 @@ class CONTENT_EXPORT RenderWidget
   // changed. If they are changed, the new value will be sent to the browser
   // process. This method does nothing when the browser process is not able to
   // handle composition range and composition character bounds.
-  void UpdateCompositionInfo(bool should_update_range);
+  // If immediate_request is true, render sends the latest composition info to
+  // the browser even if the composition info is not changed.
+  void UpdateCompositionInfo(bool immediate_request);
 
   // Change the device ICC color profile while running a layout test.
   void SetDeviceColorProfileForTesting(const std::vector<char>& color_profile);
@@ -494,6 +496,10 @@ class CONTENT_EXPORT RenderWidget
   void OnRequestTextInputStateUpdate();
 #endif
 
+  // Called by the browser process to update the cursor and composition
+  // information.
+  void OnRequestCompositionUpdate(bool immediate_request, bool monitor_request);
+
   // Notify the compositor about a change in viewport size. This should be
   // used only with auto resize mode WebWidgets, as normal WebWidgets should
   // go through OnResize.
@@ -738,6 +744,9 @@ class CONTENT_EXPORT RenderWidget
   std::deque<blink::WebTextInputInfo> text_input_info_history_;
 #endif
 
+  // True if the IME requests updated composition info.
+  bool monitor_composition_info_;
+
   std::unique_ptr<RenderWidgetScreenMetricsEmulator> screen_metrics_emulator_;
 
   // Popups may be displaced when screen metrics emulation is enabled.