Implement Skia pipelines for OpenGL and Vulkan.

Implement Skia pipelines for OpenGL and Vulkan:
base SkiaPipeline, SkiaOpenGLPipeline and SkiaVulkanPipeline.
Write unit tests for SkiaPipeline.

Test: Built and run manually on angler-eng.
Change-Id: Ie02583426cb3547541ad9bf91700602a6163ff58
diff --git a/libs/hwui/renderthread/EglManager.h b/libs/hwui/renderthread/EglManager.h
index 7349dcc..b12522e 100644
--- a/libs/hwui/renderthread/EglManager.h
+++ b/libs/hwui/renderthread/EglManager.h
@@ -31,6 +31,11 @@
 
 class Frame {
 public:
+    Frame(EGLint width, EGLint height, EGLint bufferAge)
+            : mWidth(width)
+            , mHeight(height)
+            , mBufferAge(bufferAge) { }
+
     EGLint width() const { return mWidth; }
     EGLint height() const { return mHeight; }
 
@@ -39,6 +44,7 @@
     EGLint bufferAge() const { return mBufferAge; }
 
 private:
+    Frame() {}
     friend class EglManager;
 
     EGLSurface mSurface;