Roll up patch for running layout tests under Aura.

Source/core/platform/ScrollbarThemeGtkOrAura.cpp

Index: Source/core/platform/ScrollbarThemeGtkOrAura.cpp
diff --git a/Source/core/platform/ScrollbarThemeGtkOrAura.cpp b/Source/core/platform/ScrollbarThemeGtkOrAura.cpp
index da0b4097d074cffe6ed3d4da6254ea13d1cc8f85..7900d42e403445d11c8402e2e922a119dd406f13 100644
--- a/Source/core/platform/ScrollbarThemeGtkOrAura.cpp
+++ b/Source/core/platform/ScrollbarThemeGtkOrAura.cpp
@@ -34,6 +34,7 @@
 #include "RuntimeEnabledFeatures.h"
 #include "core/platform/ScrollbarThemeOverlay.h"
 #include "core/platform/graphics/GraphicsContext.h"
+#include "platform/LayoutTestSupport.h"
 #include "platform/PlatformMouseEvent.h"
 #include "platform/scroll/ScrollbarThemeClient.h"
 #include "public/platform/Platform.h"
@@ -63,9 +64,22 @@ int ScrollbarThemeGtkOrAura::scrollbarThickness(ScrollbarControlSize controlSize
 void ScrollbarThemeGtkOrAura::paintTrackPiece(GraphicsContext* gc, ScrollbarThemeClient* scrollbar, const IntRect& rect, ScrollbarPart partType)
 {
     WebKit::WebThemeEngine::State state = scrollbar->hoveredPart() == partType ? WebKit::WebThemeEngine::StateHover : WebKit::WebThemeEngine::StateNormal;
+
+    if (isRunningLayoutTest()) {
+        if (!scrollbar->enabled())
+            state = WebKit::WebThemeEngine::StateDisabled;
+        else if (scrollbar->hoveredPart() == partType)
+            state = WebKit::WebThemeEngine::StateHot;
+        else if (scrollbar->hoveredPart() != NoPart)
+            state = WebKit::WebThemeEngine::StateHover;
+        else
+            state = WebKit::WebThemeEngine::StateNormal;
+    }
+
     IntRect alignRect = trackRect(scrollbar, false);
     WebKit::WebThemeEngine::ExtraParams extraParams;
     WebKit::WebCanvas* canvas = gc->canvas();
+    extraParams.scrollbarTrack.isBack = (partType == BackTrackPart);
     extraParams.scrollbarTrack.trackX = alignRect.x();
     extraParams.scrollbarTrack.trackY = alignRect.y();
     extraParams.scrollbarTrack.trackWidth = alignRect.width();
@@ -78,6 +92,38 @@ void ScrollbarThemeGtkOrAura::paintButton(GraphicsContext* gc, ScrollbarThemeCli
     WebKit::WebThemeEngine::Part paintPart;
     WebKit::WebThemeEngine::State state = WebKit::WebThemeEngine::StateNormal;
     WebKit::WebCanvas* canvas = gc->canvas();
+
+    if (isRunningLayoutTest()) {
+        if (scrollbar->orientation() == HorizontalScrollbar) {
+            if (part == BackButtonStartPart)
+                paintPart = WebKit::WebThemeEngine::PartScrollbarLeftArrow;
+            else if (part == ForwardButtonEndPart)
+                paintPart = WebKit::WebThemeEngine::PartScrollbarRightArrow;
+            else
+                return;
+        } else {
+            if (part == BackButtonStartPart)
+                paintPart = WebKit::WebThemeEngine::PartScrollbarUpArrow;
+            else if (part == ForwardButtonEndPart)
+                paintPart = WebKit::WebThemeEngine::PartScrollbarDownArrow;
+            else
+                return;
+        }
+
+        if (!scrollbar->enabled()) {
+            state = WebKit::WebThemeEngine::StateDisabled;
+        } else {
+            if (part == scrollbar->pressedPart())
+                state = WebKit::WebThemeEngine::StatePressed;
+            else if (part == scrollbar->hoveredPart())
+                state = WebKit::WebThemeEngine::StateDisabled;
+            else if (NoPart != scrollbar->hoveredPart())
+                state = WebKit::WebThemeEngine::StateHover;
+        }
+        WebKit::Platform::current()->themeEngine()->paint(canvas, paintPart, state, WebKit::WebRect(rect), 0);

[jamesr, 2013/11/06 21:54:09]

how is this code different from the non-testing codepath?

[Dirk Pranke, 2013/11/06 22:29:11]

Are you referring to just lines 123-124, or the whole if block? Lines 123-124
are the same, I copied them here so that we can exit early rather than mixing
flow. I can certainly remove the duplication and put the non-test code in an
else block if you'd prefer.

Generally speaking, I tried to keep the layout test code contiguous with an eye
to moving all of this out into a separate subclass in a future patch. Let me
know if you want me to add comments to indicate that or restructure the code so
that there's fewer duplicated lines instead.

[jamesr, 2013/11/06 23:16:15]

Let's optimize for how the code is in this patch, not how we think it'll be in
the future.  I think it'll be a lot easier to see what needs to be extracted if
the test-only paths are just the parts needed for tests and not duplicates of
parts of the production code.

[Dirk Pranke, 2013/11/06 23:46:38]

Okay, I was pretty sure that keeping all the code together that would need to be
in a subclass would make it easier to extract, but I don't feel strongly one way
or another (I originally wrote it the other way, in fact). So, I will change
this.

+        return;
+    }
+
     bool checkMin = false;
     bool checkMax = false;
     if (scrollbar->orientation() == HorizontalScrollbar) {
@@ -116,7 +162,7 @@ void ScrollbarThemeGtkOrAura::paintThumb(GraphicsContext* gc, ScrollbarThemeClie
     if (scrollbar->pressedPart() == ThumbPart)
         state = WebKit::WebThemeEngine::StatePressed;
     else if (scrollbar->hoveredPart() == ThumbPart)
-        state = WebKit::WebThemeEngine::StateHover;
+        state = isRunningLayoutTest() ? WebKit::WebThemeEngine::StateHot : WebKit::WebThemeEngine::StateHover;

[jamesr, 2013/11/06 21:54:09]

i think you should teach the mock WebThemeEngine to correctly handle Hot vs
Hover and not branch in the prod codepath

[Dirk Pranke, 2013/11/06 22:29:11]

I don't think I can. The theme engine is told whether a part is hot or hovered.
To figure out which was which requires context that it doesn't have. I think
perhaps an alternative is to make the non-mock implementations handle both
states and do the right thing, but I was trying to avoid changing any of the
prod implementations.

Generally speaking, there's some cleanup that can be done to restructure the
WebThemeEngine interface to get rid of some of these problems.

[jamesr, 2013/11/06 23:16:15]

It looks like what you want to do is treat StateHover as StateHot when painting
the thumb in layout tests.  What piece of information are you missing in the
WebThemeEngine implementation in order to do that?  Are there ever cases where
we paint a thumb and need to tell the difference in the mock implementation
between the two?  It looks like we're calling directly into WebThemeEngine here.

     else
         state = WebKit::WebThemeEngine::StateNormal;
     WebKit::Platform::current()->themeEngine()->paint(canvas, scrollbar->orientation() == HorizontalScrollbar ? WebKit::WebThemeEngine::PartScrollbarHorizontalThumb : WebKit::WebThemeEngine::PartScrollbarVerticalThumb, state, WebKit::WebRect(rect), 0);