webgl: optimize webgl.texSubImage2D(video) path.

content/renderer/media/android/webmediaplayer_android.cc

Index: content/renderer/media/android/webmediaplayer_android.cc
diff --git a/content/renderer/media/android/webmediaplayer_android.cc b/content/renderer/media/android/webmediaplayer_android.cc
index 4e6db8694bfc0730f3b2e3cf265ee2ca9dc854e1..69ec1a7c2a13991ceb884c0790df8f8350d1593c 100644
--- a/content/renderer/media/android/webmediaplayer_android.cc
+++ b/content/renderer/media/android/webmediaplayer_android.cc
@@ -635,8 +635,11 @@ void WebMediaPlayerAndroid::paint(blink::WebCanvas* canvas,
 
   unsigned textureId = static_cast<unsigned>(
     (bitmap_.getTexture())->getTextureHandle());
-  if (!copyVideoTextureToPlatformTexture(context3D, textureId,
-      GL_RGBA, GL_UNSIGNED_BYTE, true, false)) {
+  if (!copyVideoTextureToPlatformTexture(
+          context3D,
+          CopyVideoTextureParams(CopyVideoTextureParams::FullCopy,
+                                 GL_TEXTURE_2D, textureId, GL_RGBA,
+                                 GL_UNSIGNED_BYTE, 0, 0, 0, true, false))) {
     return;
   }
 
@@ -660,12 +663,12 @@ void WebMediaPlayerAndroid::paint(blink::WebCanvas* canvas,
 
 bool WebMediaPlayerAndroid::copyVideoTextureToPlatformTexture(
     blink::WebGraphicsContext3D* web_graphics_context,
-    unsigned int texture,
-    unsigned int internal_format,
-    unsigned int type,
-    bool premultiply_alpha,
-    bool flip_y) {
+    const CopyVideoTextureParams& params) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
+  DCHECK((params.copyType == CopyVideoTextureParams::FullCopy &&
+          !params.xoffset && !params.yoffset) ||
+         (params.copyType == CopyVideoTextureParams::SubCopy &&
+          !params.internalFormat && !params.type));
   // Don't allow clients to copy an encrypted video frame.
   if (needs_external_surface_)
     return false;
@@ -696,9 +699,17 @@ bool WebMediaPlayerAndroid::copyVideoTextureToPlatformTexture(
   // value down to get the expected result.
   // flip_y==true means to reverse the video orientation while
   // flip_y==false means to keep the intrinsic orientation.
-  web_graphics_context->copyTextureCHROMIUM(
-      GL_TEXTURE_2D, src_texture, texture, internal_format, type,
-      flip_y, premultiply_alpha, false);
+  if (params.copyType == CopyVideoTextureParams::FullCopy) {
+    web_graphics_context->copyTextureCHROMIUM(
+        params.target, src_texture, params.texture, params.internalFormat,
+        params.type, params.flipY, params.premultiplyAlpha, false);
+  } else {
+    web_graphics_context->copySubTextureCHROMIUM(
+        params.target, src_texture, params.texture, params.xoffset,
+        params.yoffset, 0, 0, video_frame->natural_size().width(),
+        video_frame->natural_size().height(), params.flipY,
+        params.premultiplyAlpha, false);
+  }
 
   web_graphics_context->deleteTexture(src_texture);
   web_graphics_context->flush();