Only show default poster when the controls attr is set

TBR=mlamouri@chromium.org

Bug: 831688
Change-Id: I2086288cef72e2c2cc7ba581d4b7fb4f00562969
Reviewed-on: https://chromium-review.googlesource.com/1007887Reviewed-by: Tommy Steimel <steimel@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550056}

third_party/WebKit/LayoutTests/compositing/squashing/dont-squash-into-videos-expected.txt

@@ -24,7 +24,7 @@
       "backgroundColor": "#ADD8E6"
     },
     {
-      "name": "LayoutFlexibleBox (relative positioned) DIV class='phase-pre-ready state-no-source use-default-poster'",
+      "name": "LayoutFlexibleBox (relative positioned) DIV class='phase-pre-ready state-no-source'",
       "bounds": [100, 100]
     },
     {

third_party/WebKit/LayoutTests/flag-specific/disable-blink-features=RootLayerScrolling/compositing/squashing/dont-squash-into-videos-expected.txt

@@ -13,7 +13,7 @@
       "backgroundColor": "#ADD8E6"
     },
     {
-      "name": "LayoutFlexibleBox (relative positioned) DIV class='phase-pre-ready state-no-source use-default-poster'",
+      "name": "LayoutFlexibleBox (relative positioned) DIV class='phase-pre-ready state-no-source'",
       "bounds": [100, 100]
     },
     {

third_party/WebKit/LayoutTests/virtual/disable-rls/compositing/squashing/dont-squash-into-videos-expected.txt

@@ -13,7 +13,7 @@
       "backgroundColor": "#ADD8E6"
     },
     {
-      "name": "LayoutFlexibleBox (relative positioned) DIV class='phase-pre-ready state-no-source use-default-poster'",
+      "name": "LayoutFlexibleBox (relative positioned) DIV class='phase-pre-ready state-no-source'",
       "bounds": [100, 100]
     },
     {

third_party/WebKit/LayoutTests/virtual/disable-spv175/compositing/squashing/dont-squash-into-videos-expected.txt

@@ -24,7 +24,7 @@
       "backgroundColor": "#ADD8E6"
     },
     {
-      "name": "LayoutFlexibleBox (relative positioned) DIV class='phase-pre-ready state-no-source use-default-poster'",
+      "name": "LayoutFlexibleBox (relative positioned) DIV class='phase-pre-ready state-no-source'",
       "bounds": [100, 100]
     },
     {

third_party/blink/renderer/modules/media_controls/media_controls_impl.cc

@@ -676,7 +676,8 @@ void MediaControlsImpl::UpdateCSSClassFromState() {
   StringBuilder builder;
   builder.Append(kStateCSSClasses[state]);
 
-  if (MediaElement().IsHTMLVideoElement() && !is_acting_as_audio_controls_ &&
+  if (MediaElement().ShouldShowControls() &&
+      MediaElement().IsHTMLVideoElement() && !is_acting_as_audio_controls_ &&
       !VideoElement().HasAvailableVideoFrame() &&
       VideoElement().PosterImageURL().IsEmpty() &&
       state <= ControlsState::kLoadingMetadata) {
@@ -847,6 +848,7 @@ void MediaControlsImpl::MaybeShow() {
     loading_panel_->OnControlsShown();
 
   timeline_->OnControlsShown();
+  UpdateCSSClassFromState();
 }
 
 void MediaControlsImpl::Hide() {
@@ -870,6 +872,8 @@ void MediaControlsImpl::Hide() {
     EndScrubbing();
   }
   timeline_->OnControlsHidden();
+
+  UpdateCSSClassFromState();
 }
 
 bool MediaControlsImpl::IsVisible() const {