Adding option for adding new tab in tab manager for chrome shell.

chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellToolbar.java

Index: chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellToolbar.java
diff --git a/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellToolbar.java b/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellToolbar.java
index 3341991646752f023c18c72d74343cc3da814e1b..8e0c2fcdb9eee7b9e0fda3e155fe99db6002f8cd 100644
--- a/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellToolbar.java
+++ b/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellToolbar.java
@@ -72,6 +72,8 @@ public class ChromeShellToolbar extends LinearLayout {
     private SuggestionPopup mSuggestionPopup;
 
     private ImageButton mStopReloadButton;
+    private ImageButton mAddButton;
+
     private int mProgress = 0;
     private boolean mLoading = true;
 
@@ -99,6 +101,8 @@ public class ChromeShellToolbar extends LinearLayout {
     public void showTab(ChromeShellTab tab) {
         if (mTab != null) mTab.removeObserver(mTabObserver);
 
+        mAddButton.setVisibility(GONE);

[Bernhard Bauer, 2014/11/04 12:22:10]

So, are we not going to show the stop/reload button again here?

In general, this seems a bit... random. What if there is some other code path
that hides or shows the tab switcher? If we want to have the invariant that the
add tab button is visible if and only if the tab switcher is visible, and the
stop/reload button is visible otherwise, we should see if there is a way to
observe state changes, instead of trying to hook into every single place where
we might hide or show the tab switcher.

[divya.bansal, 2014/11/05 09:04:22]

Done. Showing the add button when tabswitcher is shown.

+
         mTab = tab;
 
         if (mTab != null) {
@@ -143,6 +147,7 @@ public class ChromeShellToolbar extends LinearLayout {
         initializeTabSwitcherButton();
         initializeMenuButton();
         initializeStopReloadButton();
+        initializeAddButton();
     }
 
     void setMenuHandler(AppMenuHandler menuHandler) {
@@ -206,6 +211,9 @@ public class ChromeShellToolbar extends LinearLayout {
             @Override
             public void onClick(View v) {
                 if (mTabManager != null) mTabManager.toggleTabSwitcher();
+                mAddButton.setVisibility(mTabManager.isTabSwitcherVisible() ? VISIBLE : GONE);
+                mStopReloadButton.setVisibility(mTabManager.isTabSwitcherVisible()
+                        ? GONE : VISIBLE);
             }
         });
     }
@@ -242,6 +250,16 @@ public class ChromeShellToolbar extends LinearLayout {
         });
     }
 
+    private void initializeAddButton() {
+        mAddButton = (ImageButton) findViewById(R.id.add_button);
+        mAddButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                mTabManager.createNewTab();
+            }
+        });
+    }
+
     /**
      * @return Current tab that is shown by ChromeShell.
      */