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 8cb0010653d6e928733c5a46917e6a718de092ba..2b2a1634c20e751502cf68a7728fe7121da7b152 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -352,7 +352,7 @@ 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);
+  void UpdateCompositionInfo(bool should_update_range, bool force_update);
 
   // Change the device ICC color profile while running a layout test.
   void SetDeviceColorProfileForTesting(const std::vector<char>& color_profile);
@@ -481,6 +481,10 @@ class CONTENT_EXPORT RenderWidget
 
   // Called by the browser process to update text input state.
   void OnRequestTextInputStateUpdate();
+
+  // Called by the browser process to update the cursor and composition
+  // information.
+  void OnRequestCursorUpdate(int mode);
 #endif
 
   // Notify the compositor about a change in viewport size. This should be
@@ -725,6 +729,9 @@ class CONTENT_EXPORT RenderWidget
   // intentionally keep the last ack'd value to know what the browser is
   // currently aware of.
   std::deque<blink::WebTextInputInfo> text_input_info_history_;
+
+  // True if the IME requests updated composition info.
+  bool monitor_composition_info_;
 #endif
 
   std::unique_ptr<RenderWidgetScreenMetricsEmulator> screen_metrics_emulator_;