Issue #61 - Reinstate buildability with shared gkmedias dll

This fully works for splitting gkmedias.dll back out from xul with one exception
which is Skia throwing undefined externals when linking gkmedias.

gfx/skia/generate_mozbuild.py

@@ -84,6 +84,10 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':
         'skia/src/fonts/SkRemotableFontMgr.cpp',
     ]
 
+if CONFIG['GKMEDIAS_SHARED_LIBRARY']:
+    DEFINES['SKIA_DLL'] = 1
+    DEFINES['GR_DLL'] = 1
+
 # We should autogenerate these SSE related flags.
 
 if CONFIG['_MSC_VER']:

gfx/skia/moz.build

@@ -643,7 +643,6 @@ else:
         'skia/src/opts/SkBlitRow_opts_none.cpp',
     ]
 
-
 # We allow warnings for third-party code that can be updated from upstream.
 ALLOW_COMPILER_WARNINGS = True
 
@@ -694,6 +693,11 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':
         'skia/src/fonts/SkRemotableFontMgr.cpp',
     ]
 
+if CONFIG['GKMEDIAS_SHARED_LIBRARY']:
+    DEFINES['SKIA_DLL'] = 1
+    DEFINES['GR_DLL'] = 1
+    DEFINES['SK_FONT_HOST_USE_SYSTEM_SETTINGS'] = 1
+
 # We should autogenerate these SSE related flags.
 
 if CONFIG['_MSC_VER']:

gfx/skia/skia/include/utils/SkPaintFilterCanvas.h

@@ -27,7 +27,7 @@ public:
      * specified canvas.  Also copies the target canvas matrix and clip bounds.
      */
     SkPaintFilterCanvas(SkCanvas* canvas);
-
+    
     enum Type {
         kPaint_Type,
         kPoint_Type,

gfx/skia/skia/src/core/SkCanvas.cpp

@@ -22,6 +22,7 @@
 #include "SkLatticeIter.h"
 #include "SkMatrixUtils.h"
 #include "SkMetaData.h"
+#include "SkNWayCanvas.h"
 #include "SkNx.h"
 #include "SkPaintPriv.h"
 #include "SkPatchUtils.h"
@@ -45,9 +46,10 @@
 #include "GrContext.h"
 #include "GrRenderTarget.h"
 #include "SkGrPriv.h"
-
 #endif
 
+class SkNWayCanvas;
+
 #define RETURN_ON_NULL(ptr)     do { if (nullptr == (ptr)) return; } while (0)
 
 /*

gfx/skia/skia/src/ports/SkTypeface_win_dw.cpp

@@ -251,7 +251,7 @@ SkScalerContext* DWriteFontTypeface::onCreateScalerContext(const SkScalerContext
 }
 
 #ifdef MOZ_SKIA
-IDWriteRenderingParams* GetDwriteRenderingParams(bool aGDI);
+extern IDWriteRenderingParams* GetDwriteRenderingParams(bool aGDI);
 #endif
 
 void DWriteFontTypeface::onFilterRec(SkScalerContext::Rec* rec) const {