android webview: Keep zoom methods synchronous

android_webview/browser/browser_view_renderer.cc

 // Copyright 2014 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 "android_webview/browser/browser_view_renderer.h"
 
 #include <utility>
 
 #include "android_webview/browser/browser_view_renderer_client.h"
 #include "android_webview/browser/child_frame.h"
@@ skipping 393 matching lines @@
 void BrowserViewRenderer::OnDetachedFromWindow() {
   TRACE_EVENT0("android_webview", "BrowserViewRenderer::OnDetachedFromWindow");
   hardware_enabled_ = false;
   attached_to_window_ = false;
   ReturnUnusedResource(shared_renderer_state_->PassUncommittedFrameOnUI());
   ReturnResourceFromParent();
   UpdateMemoryPolicy();
   UpdateCompositorIsActive();
 }
 
+void BrowserViewRenderer::SynchronizeRendererScroll() {
+  if (!compositor_)
+    return;
+  compositor_->SynchronizeWithRenderer();
+}
+
 void BrowserViewRenderer::OnComputeScroll(base::TimeTicks animation_time) {
   if (!compositor_)
     return;
   TRACE_EVENT0("android_webview", "BrowserViewRenderer::OnComputeScroll");
   compositor_->OnComputeScroll(animation_time);
 }
 
 bool BrowserViewRenderer::IsVisible() const {
   // Ignore |window_visible_| if |attached_to_window_| is false.
   return view_visible_ && (!attached_to_window_ || window_visible_);
@@ skipping 269 matching lines @@
   base::StringAppendF(&str,
                       "overscroll_rounding_error_: %s ",
                       overscroll_rounding_error_.ToString().c_str());
   base::StringAppendF(
       &str, "on_new_picture_enable: %d ", on_new_picture_enable_);
   base::StringAppendF(&str, "clear_view: %d ", clear_view_);
   return str;
 }
 
 }  // namespace android_webview