Remove unused WebTestProxy paint/canvas code

content/shell/renderer/test_runner/test_runner.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 "content/shell/renderer/test_runner/test_runner.h"
 
 #include <limits>
 
 #include "base/logging.h"
 #include "content/shell/common/test_runner/test_preferences.h"
@@ skipping 2485 matching lines @@
   delegate_->setFocus(proxy_, value);
 }
 
 std::string TestRunner::PathToLocalResource(const std::string& path) {
   return delegate_->pathToLocalResource(path);
 }
 
 void TestRunner::SetBackingScaleFactor(double value,
                                        v8::Handle<v8::Function> callback) {
   delegate_->setDeviceScaleFactor(value);
-  proxy_->DiscardBackingStore();
   delegate_->postTask(new InvokeCallbackTask(this, callback));
 }
 
 void TestRunner::SetColorProfile(const std::string& name,
                                  v8::Handle<v8::Function> callback) {
   delegate_->setDeviceColorProfile(name);
   delegate_->postTask(new InvokeCallbackTask(this, callback));
 }
 
 void TestRunner::SetPOSIXLocale(const std::string& locale) {
@@ skipping 110 matching lines @@
 }
 
 void TestRunner::DidLosePointerLockInternal() {
   bool was_locked = pointer_locked_;
   pointer_locked_ = false;
   if (was_locked)
     web_view_->didLosePointerLock();
 }
 
 }  // namespace content