Revert of Remove DCHECK_IMPLIES/CHECK_IMPLIES.

ui/events/blink/blink_event_util.cc

 // Copyright 2015 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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/events/blink/blink_event_util.h"
 
 #include <cmath>
@@ skipping 105 matching lines @@
   //
   // The proposed extension to W3C Touch Events specifies the touch ellipse
   // using two radii along x- & y-axes and a positive acute rotation angle in
   // degrees. See:
   // http://dvcs.w3.org/hg/webevents/raw-file/default/touchevents.html
 
   float major_radius = event.GetTouchMajor(pointer_index) / 2.f;
   float minor_radius = event.GetTouchMinor(pointer_index) / 2.f;
 
   DCHECK_LE(minor_radius, major_radius);
-  DCHECK(!major_radius || minor_radius);
+  DCHECK_IMPLIES(major_radius, minor_radius);
 
   float orientation_deg = event.GetOrientation(pointer_index) * 180.f / M_PI;
   DCHECK_GE(major_radius, 0);
   DCHECK_GE(minor_radius, 0);
   DCHECK_GE(major_radius, minor_radius);
   // Orientation lies in [-180, 180] for a stylus, and [-90, 90] for other
   // touchscreen inputs. There are exceptions on Android when a device is
   // rotated, yielding touch orientations in the range of [-180, 180].
   // Regardless, normalise to [-90, 90), allowing a small tolerance to account
   // for floating point conversion.
@@ skipping 210 matching lines @@
 }
 
 WebGestureEvent CreateWebGestureEventFromGestureEventData(
     const GestureEventData& data) {
   return CreateWebGestureEvent(data.details, data.time - base::TimeTicks(),
                                gfx::PointF(data.x, data.y),
                                gfx::PointF(data.raw_x, data.raw_y), data.flags);
 }
 
 }  // namespace ui