Remove FORMAT_RGB from gfx::PngCodec

media/gpu/rendering_helper.cc

Index: media/gpu/rendering_helper.cc
diff --git a/media/gpu/rendering_helper.cc b/media/gpu/rendering_helper.cc
index 1031ed43d592484e6b38d6b182ccb571f9350337..05185c461c3b71ade2cfe6759a6412ba377ad245 100644
--- a/media/gpu/rendering_helper.cc
+++ b/media/gpu/rendering_helper.cc
@@ -710,14 +710,13 @@ void RenderingHelper::Clear() {
   thumbnails_texture_id_ = 0;
 }
 
-void RenderingHelper::GetThumbnailsAsRGB(std::vector<unsigned char>* rgb,
-                                         bool* alpha_solid,
-                                         base::WaitableEvent* done) {
+void RenderingHelper::GetThumbnailsAsRGBA(std::vector<unsigned char>* rgba,
+                                          bool* alpha_solid,
+                                          base::WaitableEvent* done) {
   CHECK(render_as_thumbnails_);
 
   const size_t num_pixels = thumbnails_fbo_size_.GetArea();
-  std::vector<unsigned char> rgba;
-  rgba.resize(num_pixels * 4);
+  rgba->resize(num_pixels * 4);
   glBindFramebufferEXT(GL_FRAMEBUFFER, thumbnails_fbo_id_);
   glPixelStorei(GL_PACK_ALIGNMENT, 1);
   // We can only count on GL_RGBA/GL_UNSIGNED_BYTE support.
@@ -728,17 +727,11 @@ void RenderingHelper::GetThumbnailsAsRGB(std::vector<unsigned char>* rgb,
                &rgba[0]);
   glBindFramebufferEXT(GL_FRAMEBUFFER,
                        gl_surface_->GetBackingFramebufferObject());
-  rgb->resize(num_pixels * 3);
-  // Drop the alpha channel, but check as we go that it is all 0xff.
+
+  // Check if the alpha channel is all 0xff.
   bool solid = true;
-  unsigned char* rgb_ptr = &((*rgb)[0]);
-  unsigned char* rgba_ptr = &rgba[0];
   for (size_t i = 0; i < num_pixels; ++i) {
-    *rgb_ptr++ = *rgba_ptr++;
-    *rgb_ptr++ = *rgba_ptr++;
-    *rgb_ptr++ = *rgba_ptr++;
-    solid = solid && (*rgba_ptr == 0xff);
-    rgba_ptr++;
+    solid = solid && ((*rgba)[4 * i + 3] == 0xff);

[scroggo_chromium, 2017/06/13 14:54:00]

Once solid is false, there's no need to continue this loop, right?

Taking a step back, this method is only called in one place, this method isn't
doing anything the client couldn't do themselves to detect alpha, and it's not
doing it along the way (e.g. it used to detect alpha while it iterated through
the pixels and copied the other components). Why not move this check into the
client code?

[msarett1, 2017/06/13 16:32:03]

sgtm, done.

   }
   *alpha_solid = solid;