Bug 1612802 - Make `IMEStateManager` stop notifying `PuppetWidget` of editor state changes while its `StopIMEStateManagement()` r=m_kato

Currently, `BrowserParent` rejects any notifications which come after
it blurs from IME focus.
https://searchfox.org/mozilla-central/rev/919607a3610222099fbfb0113c98b77888ebcbfb/dom/ipc/BrowserParent.cpp#2157,2169,2181,2192,2203,2216

But for saving unnecessary IPC messages, we should make `IMEStateManager` in
a content process stop sending notifications which occurs during its
`StopIMEStateManagement()` is called.

Differential Revision: https://phabricator.services.mozilla.com/D93176

dom/events/IMEContentObserver.cpp

@@ -476,6 +476,9 @@ nsPresContext* IMEContentObserver::GetPresContext() const {
 void IMEContentObserver::Destroy() {
   // WARNING: When you change this method, you have to check Unlink() too.
 
+  // Note that don't send any notifications later from here.  I.e., notify
+  // IMEStateManager of the blur synchronously because IMEStateManager needs to
+  // stop notifying the main process if this is requested by the main process.
   NotifyIMEOfBlur();
   UnregisterObservers();
   Clear();

dom/events/IMEStateManager.cpp

@@ -9,6 +9,7 @@
 #include "mozilla/IMEStateManager.h"
 
 #include "mozilla/Attributes.h"
+#include "mozilla/AutoRestore.h"
 #include "mozilla/EditorBase.h"
 #include "mozilla/EventListenerManager.h"
 #include "mozilla/EventStates.h"
@@ -76,6 +77,7 @@ InputContext::Origin IMEStateManager::sOrigin = InputContext::ORIGIN_MAIN;
 InputContext IMEStateManager::sActiveChildInputContext;
 bool IMEStateManager::sInstalledMenuKeyboardListener = false;
 bool IMEStateManager::sIsGettingNewIMEState = false;
+bool IMEStateManager::sCleaningUpForStoppingIMEStateManagement = false;
 
 // static
 void IMEStateManager::Init() {
@@ -203,6 +205,15 @@ void IMEStateManager::StopIMEStateManagement() {
   // NOTE: Don't set input context from here since this has already lost
   //       the rights to change input context.
 
+  // The requestee of this method in the main process must destroy its
+  // active IMEContentObserver for making existing composition end and
+  // make it be possible to start new composition in new focused process.
+  // Therefore, we shouldn't notify the main process of any changes which
+  // occurred after here.
+  AutoRestore<bool> restoreStoppingIMEStateManagementState(
+      sCleaningUpForStoppingIMEStateManagement);
+  sCleaningUpForStoppingIMEStateManagement = true;
+
   if (sTextCompositions && sPresContext) {
     NotifyIME(REQUEST_TO_COMMIT_COMPOSITION, sPresContext, nullptr);
   }
@@ -1550,12 +1561,14 @@ nsresult IMEStateManager::NotifyIME(const IMENotification& aNotification,
            "aWidget=0x%p, aBrowserParent=0x%p), sFocusedIMEWidget=0x%p, "
            "BrowserParent::GetFocused()=0x%p, sFocusedIMEBrowserParent=0x%p, "
            "aBrowserParent == BrowserParent::GetFocused()=%s, "
-           "aBrowserParent == sFocusedIMEBrowserParent=%s",
+           "aBrowserParent == sFocusedIMEBrowserParent=%s, "
+           "CanSendNotificationToTheMainProcess()=%s",
            ToChar(aNotification.mMessage), aWidget, aBrowserParent,
            sFocusedIMEWidget, BrowserParent::GetFocused(),
            sFocusedIMEBrowserParent.get(),
            GetBoolName(aBrowserParent == BrowserParent::GetFocused()),
-           GetBoolName(aBrowserParent == sFocusedIMEBrowserParent)));
+           GetBoolName(aBrowserParent == sFocusedIMEBrowserParent),
+           GetBoolName(CanSendNotificationToTheMainProcess())));
 
   if (NS_WARN_IF(!aWidget)) {
     MOZ_LOG(sISMLog, LogLevel::Error,
@@ -1565,6 +1578,8 @@ nsresult IMEStateManager::NotifyIME(const IMENotification& aNotification,
 
   switch (aNotification.mMessage) {
     case NOTIFY_IME_OF_FOCUS: {
+      MOZ_ASSERT(CanSendNotificationToTheMainProcess());
+
       // If focus notification comes from a remote browser which already lost
       // focus, we shouldn't accept the focus notification.  Then, following
       // notifications from the process will be ignored.
@@ -1632,7 +1647,10 @@ nsresult IMEStateManager::NotifyIME(const IMENotification& aNotification,
       nsCOMPtr<nsIWidget> focusedIMEWidget(sFocusedIMEWidget);
       sFocusedIMEWidget = nullptr;
       sFocusedIMEBrowserParent = nullptr;
-      return focusedIMEWidget->NotifyIME(IMENotification(NOTIFY_IME_OF_BLUR));
+      return CanSendNotificationToTheMainProcess()
+                 ? focusedIMEWidget->NotifyIME(
+                       IMENotification(NOTIFY_IME_OF_BLUR))
+                 : NS_OK;
     }
     case NOTIFY_IME_OF_SELECTION_CHANGE:
     case NOTIFY_IME_OF_TEXT_CHANGE:
@@ -1660,6 +1678,9 @@ nsresult IMEStateManager::NotifyIME(const IMENotification& aNotification,
              "is ignored because it's not for current focused IME widget"));
         return NS_OK;
       }
+      if (!CanSendNotificationToTheMainProcess()) {
+        return NS_OK;
+      }
       nsCOMPtr<nsIWidget> widget(aWidget);
       return widget->NotifyIME(aNotification);
     }

dom/events/IMEStateManager.h

@@ -78,6 +78,15 @@ class IMEStateManager {
     return sFocusedIMEBrowserParent == aBrowserParent;
   }
 
+  /**
+   * If CanSendNotificationToTheMainProcess() returns false (it should occur
+   * only in a content process), we shouldn't notify the main process of
+   * any focused editor changes since the content process was blurred.
+   */
+  static bool CanSendNotificationToTheMainProcess() {
+    return !sCleaningUpForStoppingIMEStateManagement;
+  }
+
   /**
    * Focus moved between browsers from aBlur to aFocus. (nullptr means the
    * chrome process.)
@@ -369,6 +378,10 @@ class IMEStateManager {
   static bool sIsGettingNewIMEState;
   static bool sCheckForIMEUnawareWebApps;
 
+  // Set to true only if this is an instance in a content process and
+  // only while `IMEStateManager::StopIMEStateManagement()`.
+  static bool sCleaningUpForStoppingIMEStateManagement;
+
   class MOZ_STACK_CLASS GettingNewIMEStateBlocker final {
    public:
     GettingNewIMEStateBlocker()

dom/events/TextComposition.cpp

@@ -563,7 +563,7 @@ nsresult TextComposition::RequestToCommit(nsIWidget* aWidget, bool aDiscard) {
   RefPtr<TextComposition> kungFuDeathGrip(this);
   const nsAutoString lastData(mLastData);
 
-  {
+  if (IMEStateManager::CanSendNotificationToTheMainProcess()) {
     AutoRestore<bool> saveRequestingCancel(mIsRequestingCancel);
     AutoRestore<bool> saveRequestingCommit(mIsRequestingCommit);
     if (aDiscard) {

widget/PuppetWidget.cpp

@@ -743,6 +743,8 @@ NativeIMEContext PuppetWidget::GetNativeIMEContext() {
 
 nsresult PuppetWidget::NotifyIMEOfFocusChange(
     const IMENotification& aIMENotification) {
+  MOZ_ASSERT(IMEStateManager::CanSendNotificationToTheMainProcess());
+
   if (!mBrowserChild) {
     return NS_ERROR_FAILURE;
   }
@@ -789,6 +791,8 @@ nsresult PuppetWidget::NotifyIMEOfFocusChange(
 
 nsresult PuppetWidget::NotifyIMEOfCompositionUpdate(
     const IMENotification& aIMENotification) {
+  MOZ_ASSERT(IMEStateManager::CanSendNotificationToTheMainProcess());
+
   if (NS_WARN_IF(!mBrowserChild)) {
     return NS_ERROR_FAILURE;
   }
@@ -804,8 +808,10 @@ nsresult PuppetWidget::NotifyIMEOfCompositionUpdate(
 
 nsresult PuppetWidget::NotifyIMEOfTextChange(
     const IMENotification& aIMENotification) {
+  MOZ_ASSERT(IMEStateManager::CanSendNotificationToTheMainProcess());
   MOZ_ASSERT(aIMENotification.mMessage == NOTIFY_IME_OF_TEXT_CHANGE,
              "Passed wrong notification");
+
   if (!mBrowserChild) {
     return NS_ERROR_FAILURE;
   }
@@ -835,6 +841,7 @@ nsresult PuppetWidget::NotifyIMEOfTextChange(
 
 nsresult PuppetWidget::NotifyIMEOfSelectionChange(
     const IMENotification& aIMENotification) {
+  MOZ_ASSERT(IMEStateManager::CanSendNotificationToTheMainProcess());
   MOZ_ASSERT(aIMENotification.mMessage == NOTIFY_IME_OF_SELECTION_CHANGE,
              "Passed wrong notification");
   if (!mBrowserChild) {
@@ -862,6 +869,7 @@ nsresult PuppetWidget::NotifyIMEOfSelectionChange(
 
 nsresult PuppetWidget::NotifyIMEOfMouseButtonEvent(
     const IMENotification& aIMENotification) {
+  MOZ_ASSERT(IMEStateManager::CanSendNotificationToTheMainProcess());
   if (!mBrowserChild) {
     return NS_ERROR_FAILURE;
   }
@@ -883,6 +891,7 @@ nsresult PuppetWidget::NotifyIMEOfMouseButtonEvent(
 
 nsresult PuppetWidget::NotifyIMEOfPositionChange(
     const IMENotification& aIMENotification) {
+  MOZ_ASSERT(IMEStateManager::CanSendNotificationToTheMainProcess());
   if (NS_WARN_IF(!mBrowserChild)) {
     return NS_ERROR_FAILURE;
   }