Prevent Control+two-finger-scroll from zooming the page.

content/browser/web_contents/web_contents_impl_unittest.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 "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/browser/frame_host/cross_site_transferring_request.h"
 #include "content/browser/frame_host/interstitial_page_impl.h"
 #include "content/browser/frame_host/navigation_entry_impl.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
@@ skipping 2412 matching lines @@
 
 // Tests that some mouseehweel events get turned into browser zoom requests.
 TEST_F(WebContentsImplTest, HandleWheelEvent) {
   using blink::WebInputEvent;
 
   scoped_ptr<ContentsZoomChangedDelegate> delegate(
       new ContentsZoomChangedDelegate());
   contents()->SetDelegate(delegate.get());
 
   int modifiers = 0;
-  float dy = 1;

[Daniel Erat, 2014/04/22 17:40:12]

deleted this since i didn't see much point for it -- note that |dx| is specified
inline.

   // Verify that normal mouse wheel events do nothing to change the zoom level.
   blink::WebMouseWheelEvent event =
-      SyntheticWebMouseWheelEventBuilder::Build(0, dy, modifiers, false);
+      SyntheticWebMouseWheelEventBuilder::Build(0, 1, modifiers, false);
   EXPECT_FALSE(contents()->HandleWheelEvent(event));
   EXPECT_EQ(0, delegate->GetAndResetContentsZoomChangedCallCount());
 
   modifiers = WebInputEvent::ShiftKey | WebInputEvent::AltKey;
-  event = SyntheticWebMouseWheelEventBuilder::Build(0, dy, modifiers, false);
+  event = SyntheticWebMouseWheelEventBuilder::Build(0, 1, modifiers, false);
   EXPECT_FALSE(contents()->HandleWheelEvent(event));
   EXPECT_EQ(0, delegate->GetAndResetContentsZoomChangedCallCount());
 
   // But whenever the ctrl modifier is applied, they can increase/decrease zoom.
   // Except on MacOS where we never want to adjust zoom with mousewheel.
   modifiers = WebInputEvent::ControlKey;
-  event = SyntheticWebMouseWheelEventBuilder::Build(0, dy, modifiers, false);
+  event = SyntheticWebMouseWheelEventBuilder::Build(0, 1, modifiers, false);
   bool handled = contents()->HandleWheelEvent(event);
 #if defined(OS_MACOSX)
   EXPECT_FALSE(handled);
   EXPECT_EQ(0, delegate->GetAndResetContentsZoomChangedCallCount());
 #else
   EXPECT_TRUE(handled);
   EXPECT_EQ(1, delegate->GetAndResetContentsZoomChangedCallCount());
   EXPECT_TRUE(delegate->last_zoom_in());
 #endif
 
   modifiers = WebInputEvent::ControlKey | WebInputEvent::ShiftKey |
       WebInputEvent::AltKey;
-  dy = -5;
-  event = SyntheticWebMouseWheelEventBuilder::Build(2, dy, modifiers, false);
+  event = SyntheticWebMouseWheelEventBuilder::Build(2, -5, modifiers, false);
   handled = contents()->HandleWheelEvent(event);
 #if defined(OS_MACOSX)
   EXPECT_FALSE(handled);
   EXPECT_EQ(0, delegate->GetAndResetContentsZoomChangedCallCount());
 #else
   EXPECT_TRUE(handled);
   EXPECT_EQ(1, delegate->GetAndResetContentsZoomChangedCallCount());
   EXPECT_FALSE(delegate->last_zoom_in());
 #endif
 
   // Unless there is no vertical movement.
-  dy = 0;
-  event = SyntheticWebMouseWheelEventBuilder::Build(2, dy, modifiers, false);
+  event = SyntheticWebMouseWheelEventBuilder::Build(2, 0, modifiers, false);
   EXPECT_FALSE(contents()->HandleWheelEvent(event));
   EXPECT_EQ(0, delegate->GetAndResetContentsZoomChangedCallCount());
 
-  // Ensure pointers to the delegate aren't kept beyond it's lifetime.
+  // Events containing precise scrolling deltas also shouldn't result in the
+  // zoom being adjusted, to avoid accidental adjustments caused by
+  // two-finger-scrolling on a touchpad.
+  modifiers = WebInputEvent::ControlKey;
+  event = SyntheticWebMouseWheelEventBuilder::Build(0, 5, modifiers, true);
+  EXPECT_FALSE(contents()->HandleWheelEvent(event));
+  EXPECT_EQ(0, delegate->GetAndResetContentsZoomChangedCallCount());
+
+  // Ensure pointers to the delegate aren't kept beyond its lifetime.
   contents()->SetDelegate(NULL);
 }
 
 // Tests that trackpad GesturePinchUpdate events get turned into browser zoom.
 TEST_F(WebContentsImplTest, HandleGestureEvent) {
   using blink::WebGestureEvent;
   using blink::WebInputEvent;
 
   scoped_ptr<ContentsZoomChangedDelegate> delegate(
       new ContentsZoomChangedDelegate());
@@ skipping 34 matching lines @@
       WebInputEvent::GesturePinchUpdate, WebGestureEvent::Touchscreen);
   event.data.pinchUpdate.scale = kZoomStepValue * 3;
   EXPECT_FALSE(contents()->HandleGestureEvent(event));
   EXPECT_EQ(0, delegate->GetAndResetContentsZoomChangedCallCount());
 
   // Ensure pointers to the delegate aren't kept beyond it's lifetime.
   contents()->SetDelegate(NULL);
 }
 
 }  // namespace content