Move call path for resetInputMethod

This is mostly about mechanical changes such as:

- Move InputMethodController-related logic inside InputMethodController
  and call it first - such that we can expand the logic there.
- Rename method name for better readability.

Also, there are subtle logical changes:

1) Try finishComposingText() even when the current input type is NONE.
   This should not have any effect.

2) When finishComposingText() returns false, we no longer call
   UpdateTextInputState(). This should not have any effect.

3) When finishComposingText() returns false, we no long call
   UpdateCompositionInfo(). This is used by Android and Mac.
   Previously, there was a chance that we propagate InvalidRange() all the
   way up to the keyboard app. Now ShouldUpdateCompositionInfo() returns
   false to make it clear.

This is originally found in resolving crbug.com/664317, but is also
needed for crbug.com/630137 because if we no longer cancel composition
on selection change, then WebViewTest may fail because it uses
TestWebViewClient which does not implement resetInputMethod().

BUG=664317, 630137

Review-Url: https://codereview.chromium.org/2561543003
Cr-Commit-Position: refs/heads/master@{#437854}

content/renderer/render_widget.cc

@@ -2022,6 +2022,8 @@ void RenderWidget::GetCompositionRange(gfx::Range* range) {
 bool RenderWidget::ShouldUpdateCompositionInfo(
     const gfx::Range& range,
     const std::vector<gfx::Rect>& bounds) {
+  if (!range.IsValid())
+    return false;
   if (composition_range_ != range)
     return true;
   if (bounds.size() != composition_character_bounds_.size())
@@ -2077,17 +2079,7 @@ blink::WebScreenInfo RenderWidget::screenInfo() {
 
 void RenderWidget::resetInputMethod() {
   ImeEventGuard guard(this);
-  // If the last text input type is not None, then we should finish any
-  // ongoing composition regardless of the new text input type.
-  if (text_input_type_ != ui::TEXT_INPUT_TYPE_NONE) {
-    // If a composition text exists, then we need to let the browser process
-    // to cancel the input method's ongoing composition session.
-    blink::WebInputMethodController* controller = GetInputMethodController();
-    if (controller &&
-        controller->finishComposingText(
-            WebInputMethodController::DoNotKeepSelection))
-      Send(new InputHostMsg_ImeCancelComposition(routing_id()));
-  }
+  Send(new InputHostMsg_ImeCancelComposition(routing_id()));
 
   UpdateCompositionInfo(false /* not an immediate request */);
 }

third_party/WebKit/Source/core/editing/InputMethodController.cpp

@@ -1193,6 +1193,12 @@ WebTextInputType InputMethodController::textInputType() const {
   return WebTextInputTypeNone;
 }
 
+void InputMethodController::willChangeFocus() {
+  if (!finishComposingText(DoNotKeepSelection))
+    return;
+  frame().chromeClient().resetInputMethod();
+}
+
 DEFINE_TRACE(InputMethodController) {
   visitor->trace(m_frame);
   visitor->trace(m_compositionRange);

third_party/WebKit/Source/core/editing/InputMethodController.h

@@ -103,6 +103,9 @@ class CORE_EXPORT InputMethodController final
   WebTextInputInfo textInputInfo() const;
   WebTextInputType textInputType() const;
 
+  // Call this when we will change focus.
+  void willChangeFocus();
+
  private:
   Document& document() const;
   bool isAvailable() const;

third_party/WebKit/Source/core/page/ChromeClient.h

@@ -303,7 +303,7 @@ class CORE_EXPORT ChromeClient : public HostWindow {
 
   // Input method editor related functions.
   virtual void didCancelCompositionOnSelectionChange() {}
-  virtual void willSetInputMethodState() {}
+  virtual void resetInputMethod() {}
   virtual void didUpdateTextOfFocusedElementByNonUserInput(LocalFrame&) {}
   virtual void showImeIfNeeded() {}
 

third_party/WebKit/Source/core/page/FocusController.cpp

@@ -39,6 +39,7 @@
 #include "core/editing/EditingUtilities.h"  // For firstPositionInOrBeforeNode
 #include "core/editing/Editor.h"
 #include "core/editing/FrameSelection.h"
+#include "core/editing/InputMethodController.h"
 #include "core/events/Event.h"
 #include "core/frame/FrameClient.h"
 #include "core/frame/FrameView.h"
@@ -1128,7 +1129,8 @@ bool FocusController::setFocusedElement(Element* element,
       !relinquishesEditingFocus(*oldFocusedElement))
     return false;
 
-  m_page->chromeClient().willSetInputMethodState();
+  if (oldFocusedFrame)
+    oldFocusedFrame->inputMethodController().willChangeFocus();
 
   Document* newDocument = nullptr;
   if (element)

third_party/WebKit/Source/web/ChromeClientImpl.cpp

@@ -1012,7 +1012,7 @@ void ChromeClientImpl::didCancelCompositionOnSelectionChange() {
     m_webView->client()->didCancelCompositionOnSelectionChange();
 }
 
-void ChromeClientImpl::willSetInputMethodState() {
+void ChromeClientImpl::resetInputMethod() {
   if (m_webView->client())
     m_webView->client()->resetInputMethod();
 }

third_party/WebKit/Source/web/ChromeClientImpl.h

@@ -196,7 +196,7 @@ class WEB_EXPORT ChromeClientImpl final : public ChromeClient {
   void ajaxSucceeded(LocalFrame*) override;
 
   void didCancelCompositionOnSelectionChange() override;
-  void willSetInputMethodState() override;
+  void resetInputMethod() override;
   void showImeIfNeeded() override;
 
   void registerViewportLayers() const override;