Bug 1448282 - TSFTextStore should append a pending action for dispatching keyboard event into the queue if OnUpdateComposition() is called without new range r?m_kato OnUpdateComposition() may be called without new range instance by some TIPs when they starts to modify composition string. At this timing, TSFTextStore should append a pending action for dispatching keyboard event into the queue. Without this patch, OnUpdateComposition() creates incomplete pending action for composition update and then, MaybeDispatchKeyboardEventAsProcessedByIME() appends pending action for dispatching keyboard event from another point immediately (e.g., from SetText()), then, finally, the caller of MaybeDispatchKeyboardEventAsProcessedByIME() appends another pending action for composition update with proper composition string. Therefore, the first pending action for composition update clears composition string before actually updating it with new composition string. In other words, new pending action for dispatching keyboard event splits a pending composition update. So, this patch prevents the splitting. MozReview-Commit-ID: 9pYO9pm3Vh9

--- a/widget/windows/TSFTextStore.cpp
+++ b/widget/windows/TSFTextStore.cpp
@@ -5320,16 +5320,23 @@ TSFTextStore::OnUpdateComposition(ITfCom
     MOZ_LOG(sTextStoreLog, LogLevel::Error,
       ("0x%p   TSFTextStore::OnUpdateComposition() FAILED due to "
        "different composition view specified", this));
     return E_UNEXPECTED;
   }
 
   // pRangeNew is null when the update is not complete
   if (!pRangeNew) {
+    MaybeDispatchKeyboardEventAsProcessedByIME();
+    if (mDestroyed) {
+      MOZ_LOG(sTextStoreLog, LogLevel::Error,
+        ("0x%p   TSFTextStore::OnUpdateComposition() FAILED due to "
+         "destroyed during dispatching a keyboard event", this));
+      return E_FAIL;
+    }
     PendingAction* action = LastOrNewPendingCompositionUpdate();
     action->mIncomplete = true;
     MOZ_LOG(sTextStoreLog, LogLevel::Info,
       ("0x%p   TSFTextStore::OnUpdateComposition() succeeded but "
        "not complete", this));
     return S_OK;
   }