A quick fix for Issue 18844....

webkit/glue/webview_impl.cc

 // Copyright (c) 2007-2009 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 "config.h"
 #include "build/build_config.h"
 
 #include "base/compiler_specific.h"
 MSVC_PUSH_WARNING_LEVEL(0);
 #include "CSSStyleSelector.h"
@@ skipping 792 matching lines @@
 bool WebViewImpl::KeyEventDefault(const WebKeyboardEvent& event) {
   Frame* frame = GetFocusedWebCoreFrame();
   if (!frame)
     return false;
 
   switch (event.type) {
     case WebInputEvent::Char: {
       if (event.windowsKeyCode == VKEY_SPACE) {
         int key_code = ((event.modifiers & WebInputEvent::ShiftKey) ?
                          VKEY_PRIOR : VKEY_NEXT);
-        return ScrollViewWithKeyboard(key_code);
+        return ScrollViewWithKeyboard(key_code, event.modifiers);
       }
       break;
     }
 
     case WebInputEvent::RawKeyDown: {
       if (event.modifiers == WebInputEvent::ControlKey) {
         switch (event.windowsKeyCode) {
           case 'A':
             GetFocusedFrame()->selectAll();
             return true;
           case VKEY_INSERT:
           case 'C':
             GetFocusedFrame()->executeCommand(WebString::fromUTF8("Copy"));
             return true;
           // Match FF behavior in the sense that Ctrl+home/end are the only Ctrl
           // key combinations which affect scrolling. Safari is buggy in the
           // sense that it scrolls the page for all Ctrl+scrolling key
           // combinations. For e.g. Ctrl+pgup/pgdn/up/down, etc.
           case VKEY_HOME:
           case VKEY_END:
             break;
           default:
             return false;
         }
       }
       if (!event.isSystemKey) {
-        return ScrollViewWithKeyboard(event.windowsKeyCode);
+        return ScrollViewWithKeyboard(event.windowsKeyCode, event.modifiers);
       }
       break;
     }
 
     default:
       break;
   }
   return false;
 }
 
-bool WebViewImpl::ScrollViewWithKeyboard(int key_code) {
+bool WebViewImpl::ScrollViewWithKeyboard(int key_code, int modifiers) {
   Frame* frame = GetFocusedWebCoreFrame();
   if (!frame)
     return false;
 
   ScrollDirection scroll_direction;
   ScrollGranularity scroll_granularity;
 
   switch (key_code) {
     case VKEY_LEFT:
       scroll_direction = ScrollLeft;
       scroll_granularity = ScrollByLine;
       break;
     case VKEY_RIGHT:
       scroll_direction = ScrollRight;
       scroll_granularity = ScrollByLine;
       break;
     case VKEY_UP:
       scroll_direction = ScrollUp;
+#if defined(OS_MACOSX)
+      // Many Mac applications (such as TextEdit, Safari, Firefox, etc.) scroll
+      // to the beginning of a page when typing command+up keys. It is better
+      // for Mac Chrome to emulate this behavior to improve compatibility with
+      // these applications.
+      scroll_granularity = (modifiers == WebInputEvent::MetaKey) ?
+          ScrollByDocument : ScrollByLine;
+#else
       scroll_granularity = ScrollByLine;
+#endif
       break;
     case VKEY_DOWN:
       scroll_direction = ScrollDown;
+#if defined(OS_MACOSX)
+      // Many Mac applications (such as TextEdit, Safari, Firefox, etc.) scroll
+      // to the end of a page when typing command+down keys. It is better
+      // for Mac Chrome to emulate this behavior to improve compatibility with
+      // these applications.
+      scroll_granularity = (modifiers == WebInputEvent::MetaKey) ?
+          ScrollByDocument : ScrollByLine;
+#else
       scroll_granularity = ScrollByLine;
+#endif
       break;
     case VKEY_HOME:
       scroll_direction = ScrollUp;
       scroll_granularity = ScrollByDocument;
       break;
     case VKEY_END:
       scroll_direction = ScrollDown;
       scroll_granularity = ScrollByDocument;
       break;
     case VKEY_PRIOR:  // page up
@@ skipping 1065 matching lines @@
 
   return document->focusedNode();
 }
 
 HitTestResult WebViewImpl::HitTestResultForWindowPos(const IntPoint& pos) {
   IntPoint doc_point(
       page_->mainFrame()->view()->windowToContents(pos));
   return page_->mainFrame()->eventHandler()->
       hitTestResultAtPoint(doc_point, false);
 }