Browser Side Text Input State Tracking for OOPIF.

content/browser/renderer_host/render_widget_host_view_base.h

Index: content/browser/renderer_host/render_widget_host_view_base.h
diff --git a/content/browser/renderer_host/render_widget_host_view_base.h b/content/browser/renderer_host/render_widget_host_view_base.h
index 94fbbb63af8992c4c305c64a6f0bc751540dddac..1e5b02f99ff080c92894a8387bcc99c7f5dc7643 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -41,7 +41,7 @@ class SkBitmap;
 
 struct AccessibilityHostMsg_EventParams;
 struct ViewHostMsg_SelectionBounds_Params;
-struct ViewHostMsg_TextInputState_Params;
+struct TextInputState;
 
 namespace media {
 class VideoFrame;
@@ -70,6 +70,7 @@ class SyntheticGestureTarget;
 class WebCursor;
 struct DidOverscrollParams;
 struct NativeWebKeyboardEvent;
+struct TextInputState;
 struct WebPluginGeometry;
 
 // Basic implementation shared by concrete RenderWidgetHostView subclasses.
@@ -127,6 +128,21 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   // changed since the last time.
   bool HasDisplayPropertyChanged(gfx::NativeView view);
 
+  // Text input state as last reported by the RenderWidget.
+  const TextInputState* text_input_state() const {
+    return text_input_state_.get();
+  }
+
+  // Current (cached) value of text input state. It equals text_input_state()
+  // if this is the RWHV of a child frame. If this is a root RWHV, this value
+  // is the cached value of the last reported text input state by either the
+  // root RenderWidget or the RenderWidget of one of the child frames.

[Charlie Reis, 2016/03/09 00:09:33]

This seems like a confusing method to use correctly.  If I call it on the root
RWHV, then it gives me the current TextInputState for the whole tab.  If I call
it on a child RWHV, it gives me the RWHV's own TextInputState, even if that's
not the current one.

That means all call sites would have to check whether they're calling it on the
root RWHV or not (or somehow verify that they aren't calling it for children). 
That seems quite likely to cause bugs.

Maybe there's another way to structure this?  Maybe the cached value should be
stored on another class (WebContentsImpl?) if it's a tab level concept?  Or this
method could assert or return null if called on a child RWHV?

[EhsanK, 2016/03/14 19:58:08]

Thanks for the suggestion. Your point is quite valid. I moved it up to the
WebContentsImpl which obviated the need to have
RenderWidgetHostViewBase::GetFocusedView(). Now there will be a
WebContentsImpl::GetTextInputState() which will return the cached value.

+  const TextInputState* current_text_input_state() const {
+    return cached_text_input_state_;
+  }
+
+  bool ShouldProcessTextInputState();
+
   base::WeakPtr<RenderWidgetHostViewBase> GetWeakPtr();
 
   //----------------------------------------------------------------------------
@@ -234,6 +250,21 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
                                                cc::SurfaceId original_surface,
                                                gfx::Point* transformed_point);
 
+  // This method is excusively called by the owner RenderWidgetHost to inform
+  // the view about a change in the input state which originated in the
+  // corresponding RenderWidget. This state is stored at the RWHV.
+  // Also, this change does not necessarily reflect the current state of the
+  // input since the text input  could be due to a change in the focused
+  // child-frame's (in OOPIF) or the out of process content managed by
+  // BrowserPlugin.
+  // TODO(ekaramad): Make this non-virtual if possible.
+  virtual void TextInputStateChanged(const TextInputState& params);
+
+  // Notifies the top level RenderWidgetHostView or the corresponding
+  // ui::InputMethod of a change in text input state in either this RWHV or one
+  // of the child frame's RWHV.
+  virtual void UpdateTextInputState();
+
   //----------------------------------------------------------------------------
   // The following static methods are implemented by each platform.
 
@@ -264,10 +295,6 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   // Indicates whether the page has finished loading.
   virtual void SetIsLoading(bool is_loading) = 0;
 
-  // Updates the state of the input method attached to the view.
-  virtual void TextInputStateChanged(
-      const ViewHostMsg_TextInputState_Params& params) = 0;
-
   // Cancel the ongoing composition of the input method attached to the view.
   virtual void ImeCancelComposition() = 0;
 
@@ -421,6 +448,9 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   static void DetachPluginsHelper(HWND parent);
 #endif
 
+  // Returns the currently focused RWHV.

[Charlie Reis, 2016/03/09 00:09:33]

Maybe it's worth mentioning how this relates to current_text_input_state() and
when people should call one vs the other?

[EhsanK, 2016/03/14 19:58:08]

It is removed now since the whole logic of getting the state from a focused
frame has moved up to the WebContentsImpl. I have added some comments there.
Done.

+  RenderWidgetHostViewBase* GetFocusedView();
+
   // Whether this view is a popup and what kind of popup it is (select,
   // autofill...).
   blink::WebPopupType popup_type_;
@@ -448,7 +478,6 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   // The current selection range relative to the start of the web page.
   gfx::Range selection_range_;
 
- protected:
   // The scale factor of the display the renderer is currently on.
   float current_device_scale_factor_;
 
@@ -459,6 +488,10 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   // renderer.
   bool pinch_zoom_enabled_;
 
+  // A cached value for the text input state which is used to avoid successive
+  // calls to GetFocusedView() whenever the text input state is required.

[Charlie Reis, 2016/03/09 00:09:33]

Maybe mention whether this is valid on anything but the main RWHV?

[EhsanK, 2016/03/14 19:58:08]

I guess removing it will make it simpler.

+  const TextInputState* cached_text_input_state_;
+
  private:
   void FlushInput();
 
@@ -470,6 +503,13 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
 
   base::ObserverList<RenderWidgetHostViewBaseObserver> observers_;
 
+  // The last reported input state by the RenderWidget.
+  scoped_ptr<TextInputState> text_input_state_;
+
+  // Whether there are changes in text input state which need further
+  // processing.
+  bool text_input_state_changed_;
+
   base::WeakPtrFactory<RenderWidgetHostViewBase> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewBase);