Remove clientWidth call during MediaControls::reset.

This is a merge to M48 of f003b7d .

Avoid calling clientWidth early to get the control panel width.
It can cause a crash when the HitTestCache is cleared, if the
cache was the last holder to the media element.  Normally, this
can't happen, but a callback from the WebMediaPlayer can be
scheduled between the cache becoming the last reference and the
next layout.

BUG=531259
NOTRY=true
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1578853002

Cr-Commit-Position: refs/branch-heads/2564@{#542}
Cr-Branched-From: 1283eca-refs/heads/master@{#359700}

third_party/WebKit/Source/core/html/shadow/MediaControls.cpp

@@ -260,13 +260,6 @@ void MediaControls::reset()
     m_fullScreenButton->setIsWanted(shouldShowFullscreenButton(mediaElement()));
 
     refreshCastButtonVisibilityWithoutUpdate();
-
-    // Set the panel width here, and force a layout, before the controls update.
-    // This would be harmless for the !useNewUi case too, but it causes
-    // compositing/geometry/video-fixed-scrolling.html to fail with two extra
-    // 0 height nodes in the render tree.
-    if (useNewUi)
-        m_panelWidth = m_panel->clientWidth();
 }
 
 LayoutObject* MediaControls::layoutObjectForTextTrackLayout()
@@ -652,9 +645,6 @@ void MediaControls::computeWhichControlsFit()
     if (!RuntimeEnabledFeatures::newMediaPlaybackUiEnabled())
         return;
 
-    if (!m_panelWidth)
-        return;
-
     // Controls that we'll hide / show, in order of decreasing priority.
     MediaControlElement* elements[] = {
         m_playButton.get(),
@@ -668,6 +658,18 @@ void MediaControls::computeWhichControlsFit()
         m_durationDisplay.get(),
     };
 
+    if (!m_panelWidth) {
+        // No layout yet -- hide everything, then make them show up later.
+        // This prevents the wrong controls from being shown briefly
+        // immediately after the first layout and paint, but before we have
+        // a chance to revise them.
+        for (MediaControlElement* element : elements) {
+            if (element)
+                element->setDoesFit(false);
+        }
+        return;
+    }
+
     int usedWidth = 0;
     bool droppedCastButton = false;
     // Assume that all controls require 48px.  Ideally, we could get this

third_party/WebKit/Source/core/html/shadow/MediaControlsTest.cpp

@@ -56,13 +56,14 @@ class MediaControlsTest : public testing::Test {
     virtual void SetUp()
     {
         m_pageHolder = DummyPageHolder::create(IntSize(800, 600));
-        Document& document = m_pageHolder->document();
+        Document& document = this->document();
         document.write("<video controls>");
         HTMLVideoElement& video = toHTMLVideoElement(*document.querySelector("video", ASSERT_NO_EXCEPTION));
         m_mediaControls = video.mediaControls();
     }
 
     MediaControls& mediaControls() { return *m_mediaControls; }
+    Document& document() { return m_pageHolder->document(); }
 
 private:
     OwnPtr<DummyPageHolder> m_pageHolder;
@@ -103,4 +104,15 @@ TEST_F(MediaControlsTest, HideAndReset)
     ASSERT_FALSE(isElementVisible(*panel));
 }
 
+TEST_F(MediaControlsTest, ResetDoesNotTriggerInitialLayout)
+{
+    Document& document = this->document();
+    int oldResolverCount = document.styleEngine().resolverAccessCount();
+    // Also assert that there are no layouts yet.
+    ASSERT_EQ(0, oldResolverCount);
+    mediaControls().reset();
+    int newResolverCount = document.styleEngine().resolverAccessCount();
+    ASSERT_EQ(oldResolverCount, newResolverCount);
+}
+
 } // namespace blink