[reland] Browser Side Text Input State Tracking for OOPIF (Aura Only)

content/browser/renderer_host/text_input_manager.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_BROWSER_TEXT_INPUT_MANAGER_H__
+#define CONTENT_BROWSER_TEXT_INPUT_MANAGER_H__
+
+#include <unordered_map>
+
+#include "base/observer_list.h"
+#include "content/browser/renderer_host/render_widget_host_view_base_observer.h"
+#include "content/common/content_export.h"
+#include "content/common/text_input_state.h"
+
+namespace content {
+
+class RenderWidgetHostViewBase;
+class TestTextInputManagerObserver;
+
+// A class which receives updates of Text Input State from  multiple sources and
+// decides what the new text input state is. It also notifies the observers when
+// text input state is updated.
+class CONTENT_EXPORT TextInputManager
+    : public RenderWidgetHostViewBaseObserver {
+ public:
+  // The top-level tab RWHV should be an observer of TextInputManager to get
+  // notifications about changes in TextInputState or other IME related state
+  // for child frames.
+  class CONTENT_EXPORT Observer {
+   public:
+    // Called when the TextInputState for |view| has changed from its previous
+    // value. The change is determined on each platform differently by only
+    // considering the change in the value of a subset of fields in the
+    // TextInputState.
+    virtual void OnTextInputStateUpdated(TextInputManager* text_input_manager,
+                                         RenderWidgetHostViewBase* view) {}
+
+    // Called when a view has called UpdateTextInputState on TextInputManager,
+    // regardless the call having lead to change in TextInputState. In some
+    // platforms this is necessary as it gives the tab-level |view| the chance
+    // do some other task, e.g., show IME if needed in Aura.
+    virtual void OnTextInputStateUpdateCalled(

[EhsanK, 2016/05/13 16:00:56]

shuchen@, kenrb@:
To differentiate between a 'change' and a case where we only call
'ShowImeIfNeeded' on InputMethod, I separated the observer calls.
As of now, this is only required by RenderWidgetHostViewAura. I am not sure if I
should enclose it with #ifdef?

+        TextInputManager* text_input_manager) {}
+
+    // Notifies all the observers that |text_input_manager| is being destroyed.
+    // TODO(ekaramad): All RWHV should get this call, but only the top-level
+    // RWHV for the outermost WebContents should be called on the other observer
+    // methods. We should separate the two classes of observers when resolving
+    // crbug.com/609846.
+    virtual void OnDestroyingTextInputManager(
+        TextInputManager* text_input_manager) {}
+  };
+
+  explicit TextInputManager();
+  ~TextInputManager() override;
+
+  // Returns the current text input state corresponding to |active_source_|.
+  // Users of this method should not hold on to the pointer as it might become
+  // dangling if the TextInputManager or |active_view_| might go away.
+  const TextInputState* GetTextInputState();
+
+  // Returns the currently active view. The active view is the last
+  // RenderWidgetHostViewBase which reported a |TextInputState.type| of other
+  // than ui::TEXT_INPUT_TYPE_NONE.
+  RenderWidgetHostViewBase* GetActiveView() const;
+
+  // Updates the text input state for |view|.
+  void UpdateTextInputState(RenderWidgetHostViewBase* view,
+                            const TextInputState& state);
+
+  // Registers the given |view| for tracking its TextInputState.
+  // TextInputManager will observe the lifetime of the |view|.
+  void Register(RenderWidgetHostViewBase* view);
+
+  // Clear text input state of |view| and removes TextInputManager from its
+  // observer list. It is important to call this for any RWHV being tracked
+  // before destruction of RWHV or TextInputManager.
+  void Unregister(RenderWidgetHostViewBase* view);
+
+  // Returns true if |view| is already registered.
+  bool IsRegisteredView(RenderWidgetHostViewBase* view) const;
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+ private:
+  friend class TestTextInputManagerObserver;
+
+  // RenderWidgetHostViewObserver implementation.
+  void OnRenderWidgetHostViewBaseDestroyed(
+      RenderWidgetHostViewBase* view) override;
+
+  void NotifyObserversAboutInputStateUpdate(RenderWidgetHostViewBase* view,
+                                            bool state_changed);
+
+  // The view with active text input state.
+  RenderWidgetHostViewBase* active_view_;
+
+  std::unordered_map<RenderWidgetHostViewBase*, TextInputState>
+      text_input_state_map_;
+
+  base::ObserverList<Observer> observer_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(TextInputManager);
+};
+}
+
+#endif  // CONTENT_BROWSER_TEXT_INPUT_MANAGER_H__