Remove the blocking touch handlers for the input[type=range] and add touch-action instead

third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp

Index: third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp b/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
index 90e4221c16c3c86f203ecf958624440bb553e9a0..ef95752a7c715c5351695045cbadd943364452db 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
@@ -29,6 +29,7 @@
 #include "core/css/resolver/StyleAdjuster.h"
 
 #include "core/HTMLNames.h"
+#include "core/InputTypeNames.h"
 #include "core/SVGNames.h"
 #include "core/dom/ContainerNode.h"
 #include "core/dom/Document.h"
@@ -41,6 +42,7 @@
 #include "core/html/HTMLPlugInElement.h"
 #include "core/html/HTMLTableCellElement.h"
 #include "core/html/HTMLTextAreaElement.h"
+#include "core/html/shadow/ShadowElementNames.h"
 #include "core/layout/LayoutTheme.h"
 #include "core/style/ComputedStyle.h"
 #include "core/style/ComputedStyleConstants.h"
@@ -336,6 +338,15 @@ static void adjustStyleForDisplay(ComputedStyle& style, const ComputedStyle& par
     }
 }
 
+static void adjustSliderStyle(ComputedStyle& style, Element* e, const ComputedStyle& sliderStyle)
+{
+    if (sliderStyle.appearance() == SliderVerticalPart) {
+        style.setTouchAction(TouchActionPanX);
+    } else {
+        style.setTouchAction(TouchActionPanY);
+    }
+}
+
 void StyleAdjuster::adjustComputedStyle(ComputedStyle& style, const ComputedStyle& parentStyle, Element* element)
 {
     if (style.display() != NONE) {
@@ -414,6 +425,23 @@ void StyleAdjuster::adjustComputedStyle(ComputedStyle& style, const ComputedStyl
             style.clearMultiCol();
     }
     adjustStyleForAlignment(style, parentStyle);
+

[majidvp, 2016/08/12 03:35:43]

I think tkent@ suggestion was to move this to LayoutTheme::adjustStyle.

+    // This block is for initialzation stage, when container's layoubtObject() hasn't been initialized.

[majidvp, 2016/08/12 03:35:43]

s/initialzation/initialization/

+    if (element && element->getAttribute("id") == ShadowElementNames::sliderContainer()) {
+        Element* host = element->shadowHost();
+        if (host && isHTMLInputElement(host) && static_cast<HTMLInputElement*>(host)->type() == InputTypeNames::range) {

[majidvp, 2016/08/12 03:35:43]

blink has helper function that should be used instead of such static casts. 
Here: toHTMLInputElement

+            adjustSliderStyle(style, element, host->layoutObject()->styleRef());

[majidvp, 2016/08/12 03:35:43]

Instead of passing the whole style reference as last parameter why not 
just pass in the "appearance". Although see my following comment on
how we could get rid of this.

+        }
+    }
+
+    // This block is for later stage when the <input>'s appearance changes but container's adjustComputedStyle wouldn't be called.
+    // Container's layoutObject() has been initialized this time.

[majidvp, 2016/08/12 03:35:43]

I am not an style expert but I think a better approach would be
to cascade the appearance style from input host to the slider
container appearance and just have the above logic.

This way the touch-action depends only on slider container appearance
and slider container appearance depends on input element appearance.


The cascade will be something similar to:
  LayoutSliderThumb::updateAppearance

[tkent, 2016/08/12 06:15:18]

Yes, adding -webkit-appearance:inherit to ::-webkit-slider-container section of
html.css should work.  Then, we can move the adjustment code to LayoutTheme
again.

Also, html.css should have touch-action CSS property for a case of
-webkit-appearance:none.

[sunyunjia, 2016/09/20 21:39:07]

According to https://bugs.chromium.org/p/chromium/issues/detail?id=648589, we
can't change the inline style of sliderContainer under this circumstance. Are we
going back to this logic?

+    if (element && isHTMLInputElement(element) && static_cast<HTMLInputElement*>(element)->type() == InputTypeNames::range && element->userAgentShadowRoot()) {
+        Element* container = element->userAgentShadowRoot()->getElementById(ShadowElementNames::sliderContainer());
+        if (container && container->layoutObject()) {
+            adjustSliderStyle(container->layoutObject()->mutableStyleRef(), container, style);
+        }
+    }
 }
 
 } // namespace blink