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..17a1ab505f43750ad433e81a439c0db70a939cfc 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

[kinaba, 2016/07/06 06:08:33]

Could you update the comment reflecting the force_update=true case?

[Seigo Nonaka, 2016/07/06 06:22:18]

Done.

   // 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(bool immediate_request, bool monitor_request);

[kinaba, 2016/07/06 06:08:33]

How about naming "OnRequestCompositionUpdate"?
At least for the renderer's point of view this is all about Composition, not
Cursor.

[Seigo Nonaka, 2016/07/06 06:22:18]

Make sense to me. Similarly, also I updated IPC name from Cursor to Composition
since it is actually request composition info update.

 #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_;