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 5187d3f81d6358f24b0d326fbd2a8fca54d73c2e..616967921a3544689ff86e23029b67cc4bd60f09 100644
--- a/content/renderer/media/android/webmediaplayer_android.cc
+++ b/content/renderer/media/android/webmediaplayer_android.cc
@@ -637,8 +637,9 @@ 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, GL_TEXTURE_2D, textureId,
+                                         GL_RGBA, GL_UNSIGNED_BYTE, 0, true,
+                                         false)) {
     return;
   }
 
@@ -663,6 +664,51 @@ bool WebMediaPlayerAndroid::copyVideoTextureToPlatformTexture(
     unsigned int type,
     bool premultiply_alpha,
     bool flip_y) {
+  return copyVideoTextureToPlatformTexture(web_graphics_context, GL_TEXTURE_2D,
+                                           texture, internal_format, type, 0,
+                                           premultiply_alpha, flip_y);
+}
+
+bool WebMediaPlayerAndroid::copyVideoTextureToPlatformTexture(
+    blink::WebGraphicsContext3D* web_graphics_context,
+    unsigned int target,
+    unsigned int texture,
+    unsigned int internal_format,
+    unsigned int type,
+    int level,
+    bool premultiply_alpha,
+    bool flip_y) {
+  return CopyVideoTextureToPlatformTextureInternal(
+      web_graphics_context, true, target, texture, internal_format, type, level,
+      0, 0, premultiply_alpha, flip_y);
+}
+
+bool WebMediaPlayerAndroid::copyVideoSubTextureToPlatformTexture(
+    blink::WebGraphicsContext3D* web_graphics_context,
+    unsigned int target,
+    unsigned int texture,
+    int level,
+    int xoffset,
+    int yoffset,
+    bool premultiply_alpha,
+    bool flip_y) {
+  return CopyVideoTextureToPlatformTextureInternal(
+      web_graphics_context, false, target, texture, GL_FALSE, GL_FALSE, level,
+      xoffset, yoffset, premultiply_alpha, flip_y);
+}
+
+bool WebMediaPlayerAndroid::CopyVideoTextureToPlatformTextureInternal(
+    blink::WebGraphicsContext3D* web_graphics_context,
+    bool is_full_copy,
+    unsigned int target,
+    unsigned int texture,
+    unsigned int internal_format,
+    unsigned int type,
+    int level,
+    int xoffset,
+    int yoffset,
+    bool premultiply_alpha,
+    bool flip_y) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   // Don't allow clients to copy an encrypted video frame.
   if (needs_external_surface_)
@@ -694,9 +740,16 @@ 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 (is_full_copy) {

[piman, 2015/09/04 17:34:29]

nit: maybe DCHECK that xoffset/yoffset are 0 here?

+    web_graphics_context->copyTextureCHROMIUM(target, src_texture, texture,
+                                              internal_format, type, flip_y,
+                                              premultiply_alpha, false);
+  } else {
+    web_graphics_context->copySubTextureCHROMIUM(
+        target, src_texture, texture, xoffset, yoffset, 0, 0,
+        video_frame->natural_size().width(),
+        video_frame->natural_size().height(), flip_y, premultiply_alpha, false);
+  }
 
   web_graphics_context->deleteTexture(src_texture);
   web_graphics_context->flush();