Speculative hardening of fullscreen infobar code.

While this probably isn't the principle infobar crash, it does have a
few bad smells:
1) InfoBarDelegate's already have an infobar() accessor. Use that
instead of a cached tab instance.
2) Many places in infobar code that handle user events check the
context to ensure they're still valid before handling them but this
didn't.
BUG=481758
TBR=acleung

Review URL: https://codereview.chromium.org/1322063003

Cr-Commit-Position: refs/heads/master@{#347017}
(cherry picked from commit 4d97826)

Review URL: https://codereview.chromium.org/1340693002 .

Cr-Commit-Position: refs/branch-heads/2490@{#235}
Cr-Branched-From: 7790a35-refs/heads/master@{#344925}

chrome/android/java/src/org/chromium/chrome/browser/fullscreen/FullscreenInfoBarDelegate.java

@@ -14,7 +14,7 @@
  */
 public class FullscreenInfoBarDelegate {
     private final FullscreenHtmlApiHandler mHandler;
-    private final Tab mTab;
+    private final boolean mIsForIncognitoTab;
     private long mNativeFullscreenInfoBarDelegate = 0;
 
     /**
@@ -31,7 +31,7 @@ private FullscreenInfoBarDelegate(
             FullscreenHtmlApiHandler handler, Tab tab) {
         assert tab != null;
         mHandler = handler;
-        mTab = tab;
+        mIsForIncognitoTab = tab.isIncognito();
         mNativeFullscreenInfoBarDelegate = nativeLaunchFullscreenInfoBar(tab);
     }
 
@@ -40,7 +40,7 @@ private FullscreenInfoBarDelegate(
      */
     protected void closeFullscreenInfoBar() {
         if (mNativeFullscreenInfoBarDelegate != 0) {
-            nativeCloseFullscreenInfoBar(mNativeFullscreenInfoBarDelegate, mTab);
+            nativeCloseFullscreenInfoBar(mNativeFullscreenInfoBarDelegate);
         }
     }
 
@@ -51,7 +51,7 @@ protected void closeFullscreenInfoBar() {
      */
     @CalledByNative
     private void onFullscreenAllowed(String origin) {
-        FullscreenInfo fullscreenInfo = new FullscreenInfo(origin, null, mTab.isIncognito());
+        FullscreenInfo fullscreenInfo = new FullscreenInfo(origin, null, mIsForIncognitoTab);
         fullscreenInfo.setContentSetting(ContentSetting.ALLOW);
     }
 
@@ -72,5 +72,5 @@ private void onInfoBarDismissed() {
     }
 
     private native long nativeLaunchFullscreenInfoBar(Tab tab);
-    private native void nativeCloseFullscreenInfoBar(long nativeFullscreenInfoBarDelegate, Tab tab);
+    private native void nativeCloseFullscreenInfoBar(long nativeFullscreenInfoBarDelegate);
 }

chrome/browser/android/fullscreen/fullscreen_infobar_delegate.cc

@@ -52,11 +52,10 @@ FullscreenInfoBarDelegate::~FullscreenInfoBarDelegate() {
 }
 
 void FullscreenInfoBarDelegate::CloseFullscreenInfoBar(
-    JNIEnv* env, jobject obj, jobject tab) {
+    JNIEnv* env, jobject obj) {
   j_delegate_.Reset();
-  TabAndroid* tab_android = TabAndroid::GetNativeTab(env, tab);
-  InfoBarService::FromWebContents(tab_android->web_contents())->RemoveInfoBar(
-      infobar());
+  if (infobar() && infobar()->owner())
+    infobar()->owner()->RemoveInfoBar(infobar());
 }
 
 int FullscreenInfoBarDelegate::GetIconID() const {

chrome/browser/android/fullscreen/fullscreen_infobar_delegate.h

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROME_BROWSER_ANDROID_FULLSCREEN_INFOBAR_DELEGATE_H_
-#define CHROME_BROWSER_ANDROID_FULLSCREEN_INFOBAR_DELEGATE_H_
+#ifndef CHROME_BROWSER_ANDROID_FULLSCREEN_FULLSCREEN_INFOBAR_DELEGATE_H_
+#define CHROME_BROWSER_ANDROID_FULLSCREEN_FULLSCREEN_INFOBAR_DELEGATE_H_
 
 #include <string>
 
@@ -24,7 +24,7 @@ class FullscreenInfoBarDelegate : public ConfirmInfoBarDelegate {
   ~FullscreenInfoBarDelegate() override;
 
   // Called to close the infobar.
-  void CloseFullscreenInfoBar(JNIEnv* env, jobject obj, jobject tab);
+  void CloseFullscreenInfoBar(JNIEnv* env, jobject obj);
 
   // ConfirmInfoBarDelegate:
   int GetIconID() const override;
@@ -40,4 +40,4 @@ class FullscreenInfoBarDelegate : public ConfirmInfoBarDelegate {
   DISALLOW_COPY_AND_ASSIGN(FullscreenInfoBarDelegate);
 };
 
-#endif  // CHROME_BROWSER_ANDROID_FULLSCREEN_INFOBAR_DELEGATE_H_
+#endif  // CHROME_BROWSER_ANDROID_FULLSCREEN_FULLSCREEN_INFOBAR_DELEGATE_H_