android webview: Keep zoom methods synchronous

content/browser/android/in_process/synchronous_compositor_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/android/in_process/synchronous_compositor_impl.h"
 
 #include <utility>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
@@ skipping 235 matching lines @@
                is_active);
   if (is_active_ == is_active)
     return;
 
   is_active_ = is_active;
   UpdateNeedsBeginFrames();
   if (begin_frame_source_)
     begin_frame_source_->SetBeginFrameSourcePaused(!is_active_);
 }
 
+void SynchronousCompositorImpl::SynchronizeWithRenderer() {
+  // Intentional no-op. Nothing to synchronize.
+}
+
 void SynchronousCompositorImpl::OnComputeScroll(
     base::TimeTicks animation_time) {
   if (need_animate_input_) {
     need_animate_input_ = false;
     synchronous_input_handler_proxy_->SynchronouslyAnimate(animation_time);
   }
 }
 
 void SynchronousCompositorImpl::OnNeedsBeginFramesChange(
     bool needs_begin_frames) {
@@ skipping 103 matching lines @@
   }
 }
 
 // Not using base::NonThreadSafe as we want to enforce a more exacting threading
 // requirement: SynchronousCompositorImpl() must only be used on the UI thread.
 bool SynchronousCompositorImpl::CalledOnValidThread() const {
   return BrowserThread::CurrentlyOn(BrowserThread::UI);
 }
 
 }  // namespace content