[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
new file mode 100644
index 0000000000000000000000000000000000000000..a4b702890ccc1fdd4aa1e349ce6b4790a4fdf3f6
--- /dev/null
+++ b/content/browser/renderer_host/text_input_manager.h
@@ -0,0 +1,107 @@
+// 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 text input state for |view| has been updated. If the

[kenrb, 2016/05/12 16:16:37]

nit: "If the the update"

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

Changed the comment altogether since the method signature changed.

+    // the update leads to a change in the text input state for the view (which
+    // is defined differently for each platform), then |changed| will be true.

[kenrb, 2016/05/12 16:16:37]

This could use some clarification. First, is it necessary to notify observers if
the state hasn't changed? 'has been updated' kind of implies something has
changed, but it could be clearer here that an update has been received but
possibly it hasn't changed the input state.

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

The issue, which as of now only exists in Aura, is that we have a concept of
change in TextInputState, which will lead to a call to
InputMethod->OnTextInputTypeChanged(), as well as a need to call for IME,
(InputMethod->ShowImeIfNeeded) when TextInpuState.show_ime_if_needed is true and
TextInputState.type is not none. To differentiate the two cases, I used this
boolean.

To make it clear as it is confusing as it is, I broke this method into two
smaller methods. One is only called when there is a change, and the other one is
called all the time (for Aura).

+    virtual void OnTextInputStateUpdated(TextInputManager* text_input_manager,
+                                         RenderWidgetHostViewBase* view,
+                                         bool changed) {}
+
+    // Notifies all the observers that |text_input_manager| has been destroyed.
+    // It is important for (tab-level) RWHV to update its reference to
+    // |text_input_manager|.
+    // TODO(ekaramad): This observer call is necessary for tab-level RWHV to be
+    // notified of TextInputManager going away in destruction paths where
+    // WebContentsImpl is destroyed sooner than RWHV (in Aura, this happens
+    // through deleting the window object). We should revise this later and
+    // perhaps turn the Observer into a Delegate.
+    virtual void OnTextInputManagerDestroyed(
+        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

[kenrb, 2016/05/12 16:16:37]

nit: Unneeded line break.

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

I think git cl format did this somehow. Done!

[kenrb, 2016/05/13 20:37:41]

Yes it wraps comments wrong.

+  // 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 implementations.
+  void OnRenderWidgetHostViewBaseDestroyed(
+      RenderWidgetHostViewBase* view) override;
+
+  // Notifies all the observers about an update in TextInputState by some view.
+  void NotifyObserversAboutInputStateUpdate(
+      RenderWidgetHostViewBase* updated_view,
+      bool 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__