Revert of fix uninit immediate mode member var in GrDrawingManager

src/gpu/GrDrawingManager.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrDrawingManager_DEFINED
 #define GrDrawingManager_DEFINED
 
@@ skipping 53 matching lines @@
     GrDrawingManager(GrContext* context, const GrDrawTarget::Options& optionsForDrawTargets,
                      bool isImmediateMode, GrSingleOwner* singleOwner)
         : fContext(context)
         , fOptionsForDrawTargets(optionsForDrawTargets)
         , fSingleOwner(singleOwner)
         , fAbandoned(false)
         , fAtlasTextContext(nullptr)
         , fPathRendererChain(nullptr)
         , fSoftwarePathRenderer(nullptr)
         , fFlushState(context->getGpu(), context->resourceProvider())
-        , fFlushing(false)
-        , fIsImmediateMode(isImmediateMode) {
+        , fFlushing(false) {
     }
 
     void abandon();
     void cleanup();
     void reset();
     void flush() { this->internalFlush(GrResourceCache::FlushType::kExternal); }
     void internalFlush(GrResourceCache::FlushType);
 
     friend class GrContext;  // for access to: ctor, abandon, reset & flush
 
@@ skipping 14 matching lines @@
     GrPathRendererChain*              fPathRendererChain;
     GrSoftwarePathRenderer*           fSoftwarePathRenderer;
 
     GrBatchFlushState                 fFlushState;
     bool                              fFlushing;
 
     bool                              fIsImmediateMode;
 };
 
 #endif