Fixing issues with new activity image readback

While writing the unit tests I have found problems and fixed them. Since I am not sure when the unit tests will land however (they come with the new Athena Browser test framework) I created this patch to get a workable version for Sadrul's Overview mode work.

BUG=408837
TEST=tests are in different CL which introduces Browser Tests for Athena

Review URL: https://codereview.chromium.org/611773002

Cr-Commit-Position: refs/heads/master@{#297193}

athena/content/content_proxy.cc

@@ -82,12 +82,12 @@ void ContentProxy::ContentWillUnload() {
 
 gfx::ImageSkia ContentProxy::GetContentImage() {
   // While we compress to PNG, we use the original read back.
-  if (!raw_image_.isNull() || !png_data_.get())
+  if (!png_data_.get())
     return raw_image_;
 
   // Otherwise we convert the PNG.
   std::vector<gfx::ImagePNGRep> image_reps;
-  image_reps.push_back(gfx::ImagePNGRep(png_data_, 0.0f));
+  image_reps.push_back(gfx::ImagePNGRep(png_data_, 1.0f));
   return *(gfx::Image(image_reps).ToImageSkia());
 }
 

athena/content/web_activity.cc

@@ -558,7 +558,7 @@ views::Widget* WebActivity::CreateWidget() {
 
 gfx::ImageSkia WebActivity::GetOverviewModeImage() {
   if (content_proxy_.get())
-    content_proxy_->GetContentImage();
+    return content_proxy_->GetContentImage();
   return gfx::ImageSkia();
 }