Switch to LayoutThemeMobile when emulating mobile device in DevTools.

third_party/WebKit/Source/core/layout/LayoutTheme.cpp

Index: third_party/WebKit/Source/core/layout/LayoutTheme.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTheme.cpp b/third_party/WebKit/Source/core/layout/LayoutTheme.cpp
index 293daeff0a3378129ae4e07307ba5867918591b9..67c33924a191fb3d05074a5943d3e61fd5ce1e11 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTheme.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTheme.cpp
@@ -42,6 +42,7 @@
 #include "core/html/shadow/ShadowElementNames.h"
 #include "core/html/shadow/SpinButtonElement.h"
 #include "core/html/shadow/TextControlInnerElements.h"
+#include "core/layout/LayoutThemeMobile.h"
 #include "core/page/FocusController.h"
 #include "core/page/Page.h"
 #include "core/style/ComputedStyle.h"
@@ -66,6 +67,15 @@ namespace blink {
 
 using namespace HTMLNames;
 
+LayoutTheme& LayoutTheme::theme()
+{
+    if (RuntimeEnabledFeatures::mobileLayoutThemeEnabled()) {
+        DEFINE_STATIC_REF(LayoutTheme, layoutThemeMobile, (LayoutThemeMobile::create()));

[dgozman, 2016/02/11 18:53:44]

This is the meaningful part of the patch.

[pdr., 2016/02/12 06:36:14]

This seems incorrect anytime we share a render process. For example, if the user
is emulating android on windows and opens a new tab, the new tab can have the
android theme.

I made a testcase for this bug, just emulate and click the link:
http://jsbin.com/nupahu

[dgozman, 2016/02/19 19:15:16]

I'm aware of this problem, but redesigning away from statics is too big an
effort not worth it for such a small difference in emulation. We do not pretend
to be 100% equal to android anyway.
Similar story happens with overlay scrollbars, which we switch on per-process
basis.

+        return *layoutThemeMobile;
+    }
+    return nativeTheme();
+}
+
 LayoutTheme::LayoutTheme()
     : m_hasCustomFocusRingColor(false)
 #if USE(NEW_THEME)