Audit use of m_client in WebFrameWidgetImpl and remove null checks.

third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp

Index: third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp b/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
index 5f235c711f502c0e4f278d903c1435bb9988525c..147caaab6d7f3f424c20567499e6918b90a3ae8e 100644
--- a/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
+++ b/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
@@ -188,13 +188,12 @@ void WebFrameWidgetImpl::sendResizeEventAndRepaint() {
     m_localRoot->frame()->document()->enqueueResizeEvent();
   }
 
-  if (m_client) {
-    if (isAcceleratedCompositingActive()) {
-      updateLayerTreeViewport();
-    } else {
-      WebRect damagedRect(0, 0, m_size.width, m_size.height);
-      m_client->didInvalidateRect(damagedRect);
-    }
+  DCHECK(m_client);
+  if (isAcceleratedCompositingActive()) {
+    updateLayerTreeViewport();
+  } else {
+    WebRect damagedRect(0, 0, m_size.width, m_size.height);
+    m_client->didInvalidateRect(damagedRect);
   }
 }
 
@@ -340,6 +339,7 @@ WebInputEventResult WebFrameWidgetImpl::handleInputEvent(
   AutoReset<const WebInputEvent*> currentEventChange(&m_currentInputEvent,
                                                      &inputEvent);
 
+  DCHECK(m_client);

[dcheng, 2017/03/27 04:33:24]

(Also, I'm not sure where this DCHECK comes from; it looks like most of the
other ones are things that used to be checked as an if(). Is this just out of
caution?)

   if (m_client->isPointerLocked() &&
       WebInputEvent::isMouseEventType(inputEvent.type())) {
     pointerLockMouseEvent(inputEvent);
@@ -423,8 +423,8 @@ void WebFrameWidgetImpl::scheduleAnimation() {
     m_layerTreeView->setNeedsBeginFrame();
     return;
   }
-  if (m_client)
-    m_client->scheduleAnimation();
+  DCHECK(m_client);
+  m_client->scheduleAnimation();
 }
 
 CompositorMutatorImpl& WebFrameWidgetImpl::mutator() {
@@ -831,6 +831,7 @@ WebInputEventResult WebFrameWidgetImpl::handleMouseWheel(
 
 WebInputEventResult WebFrameWidgetImpl::handleGestureEvent(
     const WebGestureEvent& event) {
+  DCHECK(m_client);

[dcheng, 2017/03/27 04:33:24]

Ditto.

   WebInputEventResult eventResult = WebInputEventResult::NotHandled;
   bool eventCancelled = false;
   switch (event.type()) {
@@ -990,13 +991,12 @@ Element* WebFrameWidgetImpl::focusedElement() const {
 }
 
 void WebFrameWidgetImpl::initializeLayerTreeView() {
-  if (m_client) {
-    DCHECK(!m_mutator);
-    m_layerTreeView = m_client->initializeLayerTreeView();
-    if (m_layerTreeView && m_layerTreeView->compositorAnimationHost()) {
-      m_animationHost = WTF::makeUnique<CompositorAnimationHost>(
-          m_layerTreeView->compositorAnimationHost());
-    }
+  DCHECK(m_client);
+  DCHECK(!m_mutator);
+  m_layerTreeView = m_client->initializeLayerTreeView();
+  if (m_layerTreeView && m_layerTreeView->compositorAnimationHost()) {
+    m_animationHost = WTF::makeUnique<CompositorAnimationHost>(
+        m_layerTreeView->compositorAnimationHost());
   }
 
   if (WebDevToolsAgentImpl* devTools = m_localRoot->devToolsAgentImpl())
@@ -1011,8 +1011,7 @@ void WebFrameWidgetImpl::initializeLayerTreeView() {
   // FIXME: only unittests, click to play, Android priting, and printing (for
   // headers and footers) make this assert necessary. We should make them not
   // hit this code and then delete allowsBrokenNullLayerTreeView.
-  DCHECK(m_layerTreeView || !m_client ||
-         m_client->allowsBrokenNullLayerTreeView());
+  DCHECK(m_layerTreeView || m_client->allowsBrokenNullLayerTreeView());
 }
 
 void WebFrameWidgetImpl::setIsAcceleratedCompositingActive(bool active) {
@@ -1027,9 +1026,6 @@ void WebFrameWidgetImpl::setIsAcceleratedCompositingActive(bool active) {
   if (m_isAcceleratedCompositingActive == active)
     return;
 
-  if (!m_client)
-    return;
-
   if (active) {
     TRACE_EVENT0("blink",
                  "WebViewImpl::setIsAcceleratedCompositingActive(true)");