MacViews: Add WidgetEventGenerator to abstract platform-specific event generation for tests.

ui/views/widget/native_widget_mac.mm

 // 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 "ui/views/widget/native_widget_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #include "ui/gfx/font_list.h"
@@ skipping 22 matching lines @@
       NSMakeRect(0, 0, params.bounds.width(), params.bounds.height());
   // TODO(tapted): Determine a good initial style mask from |params|.
   NSInteger style_mask = NSTitledWindowMask | NSClosableWindowMask |
                          NSMiniaturizableWindowMask | NSResizableWindowMask;
   base::scoped_nsobject<NSWindow> window(
       [[NSWindow alloc] initWithContentRect:content_rect
                                   styleMask:style_mask
                                     backing:NSBackingStoreBuffered
                                       defer:NO]);
   bridge_->Init(window);
+  delegate_->OnNativeWidgetCreated(true);
 }
 
 NonClientFrameView* NativeWidgetMac::CreateNonClientFrameView() {
   return NULL;
 }
 
 bool NativeWidgetMac::ShouldUseNativeFrame() const {
   return false;
 }
 
@@ skipping 364 matching lines @@
 }
 
 // static
 void NativeWidgetPrivate::ReparentNativeView(gfx::NativeView native_view,
                                              gfx::NativeView new_parent) {
   NOTIMPLEMENTED();
 }
 
 // static
 bool NativeWidgetPrivate::IsMouseButtonDown() {
-  NOTIMPLEMENTED();
-  return false;
+  return [NSEvent pressedMouseButtons] != 0;
 }
 
 // static
 bool NativeWidgetPrivate::IsTouchDown() {
   NOTIMPLEMENTED();
   return false;
 }
 
 // static
 gfx::FontList NativeWidgetPrivate::GetWindowTitleFontList() {
   NOTIMPLEMENTED();
   return gfx::FontList();
 }
 
 }  // namespace internal
 }  // namespace views