Enable video painting on Canvas for Chrome on Android.

Source/WebKit/chromium/src/WebMediaPlayerClientImpl.cpp

Index: Source/WebKit/chromium/src/WebMediaPlayerClientImpl.cpp
diff --git a/Source/WebKit/chromium/src/WebMediaPlayerClientImpl.cpp b/Source/WebKit/chromium/src/WebMediaPlayerClientImpl.cpp
index bc77af2f52cea64dd2e96a9b7a44d614c3c19777..9c757f3a1515916e118d3fb01af77071e2f91f86 100644
--- a/Source/WebKit/chromium/src/WebMediaPlayerClientImpl.cpp
+++ b/Source/WebKit/chromium/src/WebMediaPlayerClientImpl.cpp
@@ -14,6 +14,9 @@
 #include "GraphicsContext.h"
 #include "GraphicsContext3DPrivate.h"
 #include "GraphicsLayerChromium.h"
+#include "GrContext.h"
+#include "GrTexture.h"
+#include "GrTypes.h"
 #include "HTMLMediaElement.h"
 #include "IntSize.h"
 #include "KURL.h"
@@ -21,6 +24,10 @@
 #include "NotImplemented.h"
 #include "PlatformContextSkia.h"
 #include "RenderView.h"
+#include "SkRefCnt.h"
+#include "SkBitmap.h"
+#include "SkCanvas.h"
+#include "SkGrPixelRef.h"
 #include "TimeRanges.h"
 #include "WebAudioSourceProvider.h"
 #include "WebDocument.h"
@@ -620,6 +627,14 @@ void WebMediaPlayerClientImpl::paintCurrentFrameInContext(GraphicsContext* conte
     if (m_webMediaPlayer && !context->paintingDisabled()) {
         PlatformGraphicsContext* platformContext = context->platformContext();
         WebCanvas* canvas = platformContext->canvas();
+
+        // Go through the fast path trying to do a GPU-GPU texture copy without readback to system memory if possible.
+        // Otherwise, it will fallback to the normal SW path.
+        RefPtr<GraphicsContext3D> context3D = SharedGraphicsContext3D::get();
+        if (context3D && paintVideoTextureInContext(context, context3D.get()))

[Ken Russell (switch to Gerrit), 2013/04/05 22:43:38]

This is still wrong as it's discarding the incoming destination rectangle.

+            return;
+
+        // Normal pure SW path
         m_webMediaPlayer->paint(canvas, rect, platformContext->getNormalizedAlpha());
     }
 }
@@ -766,6 +781,51 @@ MediaPlayer::SupportsType WebMediaPlayerClientImpl::supportsType(const String& t
     return MediaPlayer::IsNotSupported;
 }
 
+bool WebMediaPlayerClientImpl::paintVideoTextureInContext(WebCore::GraphicsContext* context, WebCore::GraphicsContext3D* context3D)

[Ken Russell (switch to Gerrit), 2013/04/05 22:43:38]

Either this needs to be made to work correctly on all platforms (it definitely
won't; see above) or it should be #ifdef'd so that on !OS_ANDROID it immediately
returns false.

+{
+    if (!context || !m_webMediaPlayer || context->paintingDisabled())
+        return false;
+
+    Extensions3D* extensions = context3D->getExtensions();
+    if (!extensions || !extensions->supports("GL_CHROMIUM_copy_texture") || !extensions->supports("GL_CHROMIUM_flipy")
+        || !context3D->makeContextCurrent())
+        return false;
+
+    WebGraphicsContext3D* webGraphicsContext3D = GraphicsContext3DPrivate::extractWebGraphicsContext3D(context3D);
+    PlatformGraphicsContext* platformContext = context->platformContext();
+    WebCanvas* canvas = platformContext->canvas();
+
+    // Create a temporary RGBA texture based SkBitmap where the video will be copied into.
+    // The bitmap's size is the same as the video.
+    unsigned int videoWidth = naturalSize().width();
+    unsigned int videoHeight = naturalSize().height();
+    GrTextureDesc desc;
+    desc.fConfig = kSkia8888_GrPixelConfig;
+    desc.fWidth = videoWidth;
+    desc.fHeight = videoHeight;
+    desc.fOrigin = kTopLeft_GrSurfaceOrigin;
+    desc.fFlags = (kRenderTarget_GrTextureFlagBit | kNoStencil_GrTextureFlagBit);
+    GrContext* ct = context3D->grContext();
+    if (!ct)
+        return false;
+    SkAutoTUnref<GrTexture> texture(ct->createUncachedTexture(desc, NULL, 0));
+    if (!texture.get())
+        return false;
+    unsigned int textureId = static_cast<unsigned int>(texture->getTextureHandle());
+
+    // Copy video texture to bitmap texture.
+    if (!m_webMediaPlayer->copyVideoTextureToPlatformTexture(webGraphicsContext3D, textureId, 0, GraphicsContext3D::RGBA, true, false)) { return false; }
+
+    SkBitmap bitmap;
+    bitmap.setConfig(SkBitmap::kARGB_8888_Config, videoWidth, videoHeight);
+    bitmap.setPixelRef(new SkGrPixelRef(texture))->unref();
+
+    // Draw the texture based bitmap onto the Canvas. If the canvas is hardware based, this will do a GPU-GPU texture copy. If the canvas is software based,
+    // the texture based bitmap will be readbacked to system memory then draw onto the canvas.
+    canvas->drawBitmap(bitmap, 0, 0);
+    return true;
+}
+
 void WebMediaPlayerClientImpl::startDelayedLoad()
 {
     ASSERT(m_delayingLoad);