PDF Viewer - PageUp/Down don't move pdf by page size in FitToPage mode

pdf/instance.cc

 // Copyright (c) 2012 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 "pdf/instance.h"
 
 #include <algorithm>  // for min()
 #define _USE_MATH_DEFINES  // for M_PI
 #include <cmath>      // for log() and pow()
 #include <math.h>
@@ skipping 761 matching lines @@
 void Instance::SelectFindResult(bool forward) {
   engine_->SelectFindResult(forward);
 }
 
 void Instance::StopFind() {
   engine_->StopFind();
 }
 
 void Instance::Zoom(double scale, bool text_only) {
   UserMetricsRecordAction("PDF.ZoomFromBrowser");
+
+  // If the zoom level doesn't change it means that this zoom change might have
+  // been initiated by the plugin. In that case, we don't want to change the
+  // zoom mode to ZOOM_SCALE as it may have been intentionally set to
+  // ZOOM_FIT_TO_PAGE or some other value when the zoom was last changed.
+  if (scale == zoom_)
+    return;
+
   SetZoom(ZOOM_SCALE, scale);
 }
 
 void Instance::ZoomChanged(double factor) {
   if (full_)
     Zoom_Dev::ZoomChanged(factor);
 }
 
 void Instance::OnPaint(const std::vector<pp::Rect>& paint_rects,
                        std::vector<PaintManager::ReadyRect>* ready,
@@ skipping 1969 matching lines @@
   return instance_->HasScriptableMethod(name, exception);
 }
 
 pp::Var PDFScriptableObject::Call(const pp::Var& method,
                                   const std::vector<pp::Var>& args,
                                   pp::Var* exception) {
   return instance_->CallScriptableMethod(method, args, exception);
 }
 
 }  // namespace chrome_pdf