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

content/browser/renderer_host/dip_util.h

Index: content/browser/renderer_host/dip_util.h
diff --git a/content/browser/renderer_host/dip_util.h b/content/browser/renderer_host/dip_util.h
index 4da0012f7c84c8cc61ec0267aa8424c6952f3670..c079be271113af6a379c3a35dd1a8c0943cac046 100644
--- a/content/browser/renderer_host/dip_util.h
+++ b/content/browser/renderer_host/dip_util.h
@@ -7,6 +7,10 @@
 
 #include "content/common/content_export.h"
 
+namespace cc {
+class CompositorFrameMetadata;
+}
+
 namespace gfx {
 class Point;
 class Rect;
@@ -29,6 +33,15 @@ CONTENT_EXPORT gfx::Size ConvertViewSizeToPixel(
 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_