Touch emulator: enables double tap support for pages similar to Chrome on Android.

content/browser/renderer_host/dip_util.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_DIP_UTIL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_DIP_UTIL_H_
 
 #include "content/common/content_export.h"
 
+namespace cc {
+class CompositorFrameMetadata;
+}
+
 namespace gfx {
 class Point;
 class Rect;
 class Size;
 }  // namespace gfx
 
 namespace content {
 class RenderWidgetHostView;
 
 // Returns scale factor of the display nearest to |view|.
 // Returns 1.0f if the platform does not support DIP.
 CONTENT_EXPORT float GetScaleFactorForView(const RenderWidgetHostView* view);
 
 // Utility functions that convert point/size/rect between DIP and pixel
 // coordinate system.
 CONTENT_EXPORT gfx::Point ConvertViewPointToDIP(
     const RenderWidgetHostView* view, const gfx::Point& point_in_pixel);
 CONTENT_EXPORT gfx::Size ConvertViewSizeToPixel(
     const RenderWidgetHostView* view, const gfx::Size& size_in_dip);
 CONTENT_EXPORT gfx::Rect ConvertViewRectToPixel(
     const RenderWidgetHostView* view, const gfx::Rect& rect_in_dip);
 
+// Decides whether to enable/disable double tap zoom for a page.
+// By default returns |true|, except for the following cases:
+// - pages that have a width=device-width or narrower viewport
+//   (indicating that this is a mobile-optimized or responsive
+//   web design, so text will be legible without zooming);
+// - pages that prevent zooming in or out.
+CONTENT_EXPORT bool IsMobileOptimizedFrame(
+    const cc::CompositorFrameMetadata& frame_metadata);
+
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_DIP_UTIL_H_