Bug 1418747 - ContentCacheInParent needs to initialize mPendingCommitLength with 0 when it's created r?m_kato ContentCacheInParent::mPendingCommitLength is never initialized until it receives eCompositionCommit(AsIs) event from widget or receives the latest content from the remote process when there is a composition. The bug is, immediately after dispatching eCompositionStart and first eCompositionChange event, MS Pinyin tries to query the character at caret, but ContentCacheInParent::HandleQueryContentEvent() tries to resolve related position of an eQueryTextRect event with the uninitialized mPendingCommitLength. Therefore, the query almost always fails and MS Pinyin gives up to show its candidate window. This patch just initializes the member with 0. MozReview-Commit-ID: JyYNqi8hoTa

--- a/widget/ContentCache.cpp
+++ b/widget/ContentCache.cpp
@@ -515,16 +515,17 @@ ContentCacheInChild::SetSelection(nsIWid
  *****************************************************************************/
 
 ContentCacheInParent::ContentCacheInParent(TabParent& aTabParent)
   : ContentCache()
   , mTabParent(aTabParent)
   , mCommitStringByRequest(nullptr)
   , mPendingEventsNeedingAck(0)
   , mCompositionStartInChild(UINT32_MAX)
+  , mPendingCommitLength(0)
   , mPendingCompositionCount(0)
   , mWidgetHasComposition(false)
   , mIsPendingLastCommitEvent(false)
 {
 }
 
 void
 ContentCacheInParent::AssignContent(const ContentCache& aOther,