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

content/browser/renderer_host/text_input_manager.h

Index: content/browser/renderer_host/text_input_manager.h
diff --git a/content/browser/renderer_host/text_input_manager.h b/content/browser/renderer_host/text_input_manager.h
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index 0000000000000000000000000000000000000000..c14a502f22bd25a6a27b3e70eefd5eed058f6504
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+++ b/content/browser/renderer_host/text_input_manager.h
@@ -0,0 +1,95 @@
+// 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_RENDERER_HOST_TEXT_INPUT_MANAGER_H__
+#define CONTENT_BROWSER_RENDERER_HOST_TEXT_INPUT_MANAGER_H__
+
+#include <unordered_map>
+
+#include "base/observer_list.h"
+#include "content/common/content_export.h"
+#include "content/common/text_input_state.h"
+
+namespace content {
+
+class RenderWidgetHostView;
+class RenderWidgetHostViewBase;
+class WebContents;
+
+// A class which receives updates of TextInputState from multiple sources and
+// decides what the new TextInputState is. It also notifies the observers when
+// text input state is updated.
+class CONTENT_EXPORT TextInputManager {
+ public:
+  // The tab's top-level 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 a view has called UpdateTextInputState on TextInputManager.
+    // If the call has led to a change in TextInputState, |did_update_state| is
+    // true. In some plaforms, we need this update even when the state has not
+    // changed (e.g., Aura for updating IME).
+    virtual void OnUpdateTextInputStateCalled(
+        TextInputManager* text_input_manager,
+        RenderWidgetHostViewBase* updated_view,
+        bool did_update_state) {}
+  };
+
+  TextInputManager();
+  ~TextInputManager();
+
+  // Returns the currently active view (i.e., the RWHV with a focused <input>
+  // element), or nullptr if none exist. The |active_view_| cannot have a
+  // |TextInputState.type| of ui::TEXT_INPUT_TYPE_NONE.
+  RenderWidgetHostViewBase* GetActiveView() const;
+
+  // Returns the TextInputState corresponding to |active_view_|.
+  // 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();
+
+  // Updates the TextInputState 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|.

[Charlie Reis, 2016/06/02 22:03:29]

This is expected to be called for all views (including children), right?  Can we
add that to the comment?

[EhsanK, 2016/06/03 17:00:34]

Done. Also modified a bit as TextInputManager is not observing view but rather
view unregisters from TextInputManager when it is destroyed.

+  void Register(RenderWidgetHostViewBase* view);
+
+  // Clears the TextInputState from the |view|. If |view == active_view_|, this
+  // call will lead to a TextInputState update since the TextInputState.type
+  // should be reset to none.
+  void Unregister(RenderWidgetHostViewBase* view);
+
+  // Returns true if |view| is already registered.
+  bool IsRegistered(RenderWidgetHostViewBase* view) const;
+
+  // Add and remove observers for notifications regarding updates in the
+  // TextInputState. Clients must be sure to remove themselves before they go
+  // away.
+  void AddObserver(Observer* observer);

[Charlie Reis, 2016/06/02 22:03:29]

In contrast, I think we only expect this to be called for the top-level / native
view, right?  (Do we only have multiple observers in the case of tests?  That's
fine, but might be worth mentioning.)

[EhsanK, 2016/06/03 17:00:34]

At any point in time, we might have more than 2. The observers remove themselves
from the list when destroyed. But I might be using (now or later) multiple test
observers within the same test. But apart from the tests, tab's RWHV must be the
only one.

+  void RemoveObserver(Observer* observer);
+
+ private:
+  friend bool GetTextInputTypeForView(WebContents* web_contents,
+                                      RenderWidgetHostView* view,
+                                      ui::TextInputType* type);
+
+  void NotifyObserversAboutInputStateUpdate(RenderWidgetHostViewBase* view,
+                                            bool did_update_state);
+
+  // 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_RENDERER_HOST_TEXT_INPUT_MANAGER_H__