rendering_helper - Unbind the thumbnail texture.

Otherwise, before the ActiveTexture0 binding to other texture,
the thumbnail texture will be blended with other decoded frames.

This can be observed with low rendering fps on ARM CrOS device.

BUG=None
TEST=Run the vda_unittest on arm cros device.

Review URL: https://codereview.chromium.org/367373008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@281735 0039d316-1c4b-4281-b951-d872f2087c98

content/common/gpu/media/rendering_helper.cc

@@ -275,6 +275,7 @@ void RenderingHelper::Initialize(const RenderingHelperParams& params,
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glBindTexture(GL_TEXTURE_2D, 0);
 
     glBindFramebufferEXT(GL_FRAMEBUFFER, thumbnails_fbo_id_);
     glFramebufferTexture2DEXT(GL_FRAMEBUFFER,