Refactoring Canvas2DLayerBridge to make it easier to write unit tests

Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp

Index: Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp
diff --git a/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp b/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp
index 3e9a705859bed05d9177823dc8e2cc40cb2aba9d..ca0887e02f0870dfc9d96be94da03b6157d4f91b 100644
--- a/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp
+++ b/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp
@@ -44,35 +44,18 @@ using WebKit::WebGraphicsContext3D;
 
 namespace WebCore {
 
-static SkSurface* createSurface(GraphicsContext3D* context3D, const IntSize& size)
-{
-    ASSERT(!context3D->webContext()->isContextLost());
-    GrContext* gr = context3D->grContext();
-    if (!gr)
-        return 0;
-    gr->resetContext();
-    SkImage::Info info;
-    info.fWidth = size.width();
-    info.fHeight = size.height();
-    info.fColorType = SkImage::kPMColor_ColorType;
-    info.fAlphaType = SkImage::kPremul_AlphaType;
-    return SkSurface::NewRenderTarget(gr, info);
-}
-
-PassOwnPtr<Canvas2DLayerBridge> Canvas2DLayerBridge::create(PassRefPtr<GraphicsContext3D> context, const IntSize& size, OpacityMode opacityMode)
+PassOwnPtr<Canvas2DLayerBridge> Canvas2DLayerBridge::create(PassOwnPtr<Helper> helper, const IntSize& size, OpacityMode opacityMode)
 {
     TRACE_EVENT_INSTANT0("test_gpu", "Canvas2DLayerBridgeCreation");
-    SkAutoTUnref<SkSurface> surface(createSurface(context.get(), size));
-    if (!surface.get())
-        return PassOwnPtr<Canvas2DLayerBridge>();
-    SkDeferredCanvas* canvas = new SkDeferredCanvas(surface);
-    OwnPtr<Canvas2DLayerBridge> layerBridge = adoptPtr(new Canvas2DLayerBridge(context, canvas, opacityMode));
+    bool success;
+    OwnPtr<Canvas2DLayerBridge> layerBridge = adoptPtr(new Canvas2DLayerBridge(helper, size, opacityMode, &success));
+    if (!success)
+        layerBridge.clear();
     return layerBridge.release();
 }
 
-Canvas2DLayerBridge::Canvas2DLayerBridge(PassRefPtr<GraphicsContext3D> context, SkDeferredCanvas* canvas, OpacityMode opacityMode)
-    : m_canvas(canvas)
-    , m_context(context)
+Canvas2DLayerBridge::Canvas2DLayerBridge(PassOwnPtr<Helper> helper, const IntSize& size, OpacityMode opacityMode, bool* success)
+    : m_helper(helper)
     , m_bytesAllocated(0)
     , m_didRecordDrawCommand(false)
     , m_surfaceIsValid(true)
@@ -82,6 +65,15 @@ Canvas2DLayerBridge::Canvas2DLayerBridge(PassRefPtr<GraphicsContext3D> context,
     , m_prev(0)
     , m_lastImageId(0)
 {
+    ASSERT(success);
+    m_context = m_helper->getContext();
+    SkAutoTUnref<SkSurface> surface(m_helper->createSurface(m_context.get(), size));
+    if (!surface.get()) {
+        *success = false;
+        return;
+    }
+    m_canvas = new SkDeferredCanvas(surface);
+
     ASSERT(m_canvas);
     // Used by browser tests to detect the use of a Canvas2DLayerBridge.
     TRACE_EVENT_INSTANT0("test_gpu", "Canvas2DLayerBridgeCreation");
@@ -91,6 +83,7 @@ Canvas2DLayerBridge::Canvas2DLayerBridge(PassRefPtr<GraphicsContext3D> context,
     GraphicsLayer::registerContentsLayer(m_layer->layer());
     m_layer->setRateLimitContext(m_rateLimitingEnabled);
     m_canvas->setNotificationClient(this);
+    *success = true;
 }
 
 Canvas2DLayerBridge::~Canvas2DLayerBridge()
@@ -196,13 +189,13 @@ bool Canvas2DLayerBridge::isValid()
         // Attempt to recover.
         m_layer->clearTexture();
         m_mailboxes.clear();
-        RefPtr<GraphicsContext3D> sharedContext = SharedGraphicsContext3D::get();
+        RefPtr<GraphicsContext3D> sharedContext = m_helper->getContext();
         if (!sharedContext || sharedContext->webContext()->isContextLost()) {
             m_surfaceIsValid = false;
         } else {
             m_context = sharedContext;
             IntSize size(m_canvas->getTopDevice()->width(), m_canvas->getTopDevice()->height());
-            SkAutoTUnref<SkSurface> surface(createSurface(m_context.get(), size));
+            SkAutoTUnref<SkSurface> surface(m_helper->createSurface(m_context.get(), size));
             if (surface.get()) {
                 m_canvas->setSurface(surface.get());
                 m_surfaceIsValid = true;
@@ -249,33 +242,37 @@ bool Canvas2DLayerBridge::prepareMailbox(WebKit::WebExternalTextureMailbox* outM
         return false;
     m_lastImageId = image->uniqueID();
 
-    mailboxInfo = createMailboxInfo();
-    mailboxInfo->m_status = MailboxInUse;
-    mailboxInfo->m_image.swap(&image);
-    // Because of texture sharing with the compositor, we must invalidate
-    // the state cached in skia so that the deferred copy on write
-    // in SkSurface_Gpu does not make any false assumptions.
-    mailboxInfo->m_image->getTexture()->invalidateCachedState();
-
-    ASSERT(mailboxInfo->m_mailbox.syncPoint == 0);
-    ASSERT(mailboxInfo->m_image.get());
-    ASSERT(mailboxInfo->m_image->getTexture());
-
-    m_context->bindTexture(GraphicsContext3D::TEXTURE_2D, mailboxInfo->m_image->getTexture()->getTextureHandle());
-    m_context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_MAG_FILTER, GraphicsContext3D::LINEAR);
-    m_context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_MIN_FILTER, GraphicsContext3D::LINEAR);
-    m_context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_WRAP_S, GraphicsContext3D::CLAMP_TO_EDGE);
-    m_context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_WRAP_T, GraphicsContext3D::CLAMP_TO_EDGE);
-    context()->produceTextureCHROMIUM(GraphicsContext3D::TEXTURE_2D, mailboxInfo->m_mailbox.name);
-    context()->flush();
-    mailboxInfo->m_mailbox.syncPoint = context()->insertSyncPoint();
-    m_context->bindTexture(GraphicsContext3D::TEXTURE_2D, 0);
-    // Because we are changing the texture binding without going through skia,
-    // we must dirty the context.
-    m_context->grContext()->resetContext(kTextureBinding_GrGLBackendState);
-
-    *outMailbox = mailboxInfo->m_mailbox;
-    return true;
+    GrTexture* texture = image->getTexture();
+    if (texture) {

[jamesr, 2013/08/05 22:56:36]

early return on failure would make this function a lot shorter and avoid
changing the indentation on so many lines

+        mailboxInfo = createMailboxInfo();
+        mailboxInfo->m_status = MailboxInUse;
+        mailboxInfo->m_image.swap(&image);
+        // Because of texture sharing with the compositor, we must invalidate
+        // the state cached in skia so that the deferred copy on write
+        // in SkSurface_Gpu does not make any false assumptions.
+        texture->invalidateCachedState();
+
+        ASSERT(!mailboxInfo->m_mailbox.syncPoint);
+        ASSERT(mailboxInfo->m_image.get());
+
+        m_context->bindTexture(GraphicsContext3D::TEXTURE_2D, texture->getTextureHandle());
+        m_context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_MAG_FILTER, GraphicsContext3D::LINEAR);
+        m_context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_MIN_FILTER, GraphicsContext3D::LINEAR);
+        m_context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_WRAP_S, GraphicsContext3D::CLAMP_TO_EDGE);
+        m_context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_WRAP_T, GraphicsContext3D::CLAMP_TO_EDGE);
+        context()->produceTextureCHROMIUM(GraphicsContext3D::TEXTURE_2D, mailboxInfo->m_mailbox.name);
+        context()->flush();
+        mailboxInfo->m_mailbox.syncPoint = context()->insertSyncPoint();
+        m_context->bindTexture(GraphicsContext3D::TEXTURE_2D, 0);
+        // Because we are changing the texture binding without going through skia,
+        // we must dirty the context.
+        m_context->grContext()->resetContext(kTextureBinding_GrGLBackendState);
+        *outMailbox = mailboxInfo->m_mailbox;
+        return true;
+    }
+    // TODO: Perform texture upload for cases where image is in RAM. Required for crbug.com/265849
+
+    return false;
 }
 
 Canvas2DLayerBridge::MailboxInfo* Canvas2DLayerBridge::createMailboxInfo() {